EMBRYOLOGY. 
THE study of the transitional stages through which plants 
and animals pass from the early to the mature condition is 
not only of immense importance to the Physiologist, but 
equally so to the Zoologist, Botanist, and Geologist. Not- 
withstanding that some knowledge, at least, of Embryology 
is demanded in the study of Biology, the subject is com- 
paratively little cultivated, owing, probably, to the limited 
means of obtaining material, and the difficult manipulation 
required in this kind of work. Nevertheless, since 1759, 
the year in which Wolff published his “ Theoria Genera- 
tionis," there have appeared from time to time Embryologists 
like Von Baer, Schleiden, Schwann, Coste, Remak, Rathke, 
etc., who, after overcoming the difficulties inherent to the 
nature of their studies, left treatises which will always be 
models of scientific work and philosophic thought. Our 
prescribed limits only permit of briefly calling attention to 
some of the conclusions of Embryology, pointing out the 
manner in which they confirm the theory of the evolution 
of life as deduced from the structure and petrified remains 
of the vegetal and animal kingdoms. Those who are 
ignorant of the early stages of plants and animals will 
hardly believe that beings so different as sea-weed, oaks, 
star-fishes, mollusca, guinea-pigs, rabbits, dogs, and men 
begin their life in the same way; yet Fig. 160 represents 
equally well the cell, or primitive stage, of any of the 
plants or animals just mentioned. Confining ourselves for 
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