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well represented through untold ages from Cambrian times to the present day. Their remains, especially of the Ostracoda and Phyllopoda, occur in all formations, and in some are so abundant as to give a peculiar foliated character to the rock containing them.

A few books of reference may not be unwelcome to the student. Before all the very complete manual of the British Entomostraca by Dr. Baird, published by the Ray Society; then the portions bearing upon the subject in Professor Huxley’s "Anatomy of the Invertebrate Animals," and Professor Nicholson's "Zoology and Palæontology;" lastly, the splendid monographs on the fossils of the group by Professor Rupert Jones, the Rev. H. W. Crosskey, and ethers, published by the Palæontotogical Society. With such help, the systematic study of our old friends, the so-called water-fleas, will be found replete with interest.

ln the year 1865 I read a paper to the British Association for the Advancement of Science, an abstract of which was printed in their Transactions, to show the relation which existed between the chlorophyll-body and the starch granule. At the present time the views of some of the most eminent botanists of Germany appear to me to be, to a certain extent, approaching to the conclusions to which I have referred. What these conclusions are it is my purpose to show.

If we refer to the great English botanists of twenty years ago, we shall find them describing chlorophyll as a "vital secretion" sui generis or independent body.

One of our great authors of that period, who wrote on this subject, thus expresses himself in his Introduction to Botany^[1]:—"Chlorophyll is a 'vital secretion', and comprises 'coloured granules' of a 'spheroidal and irregular figure.' They 'consist of a semifluid, gelatinous substance, which seems to be a coagulum of the fluid contents of the cells.'"

Nägeli states that the parent cells of chlorophyll "are only half the size of starch," and that "they occur in company with starch grains."

In 1851 Dr. J. S. Quekett delivered, at the Royal College of Surgeons of England, a course of lectures on Histology, and on the subject of chlorophyll occurs the following:—"The green colour, so universally present in plants, is due to a more or less solid material contained in cells, and termed chlorophylls, or green vegetable wax." it consists of minute spherical or oval particles.

Dr. J. H. Balfour, in his Manual of Botany, 1860, page 11, states that "Chlorophylle, or the green colouring matter of plants, floats in the fluid of calls, accompanied by starch grains, it differs from starch in being confined to the superficial parenchyma, and in being principally associated with the phenomena of active vegetable life. It has a granular form, is soluble in alcohol, appears to be analogous to wax in its composition, and is developed under the agency of light."