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POPULAR SCIENCE REVIEW. 
The Development of the Hydrozoa. — In an important memoir on the struc- 
ture of certain of the hydrozoa, Herr Reichert denies that these animals can 
he compared with the early phases of the vertebrate ovum. In one of his 
tabulated conclusions, he says, “'the comparison of the hollow body of the 
hydrozoa to the first stages of development of the organism of the higher 
vertebrata undertaken by Huxley, and afterwards by Kolliker, has no 
foundation, in fact ; it even proceeds from erroneous suppositions, both as to 
the nature and signification of the first foundation of the vertebrate animal, 
and with regard to the structure of the body of the hydrozoa.” This is a 
very decided assertion on the part of Professor Reichert, and we confess 
that we see some difficulty in the way of its acceptance. 
The Circulation of Helix Pomatia. — On this point an extremely valuable 
paper has been published by Mr. C. Robertson, Demonstrator at Oxford. 
Mr. Robertson states that he has proved the existence of a general capillary 
system of blood-vessels in this animal. We, ourselves, have not been able 
to discern such a condition of parts in Limax maximus. Dr. Robertson’s - 
memoir is an important contribution to molluscan anatomy. — Vide Annals 
of Natural History , January. 
