368 On the Form of the Globules of the Blood. 



of the mammifera a circular form, and consequently they also 

 add to the singularity of the exception established by this 

 young micrographer, an exception which shews how much 

 caution is necessary when, in compai-ative physiology, one draws 

 general conclusions from even a very considerable number of 

 particular facts. The study of organised bodies reveals to us 

 the tendencies of nature, but has conducted us very rarely to 

 the knowledge of the laws which govern her works. 



It were much to be wished that naturalists would not allow 

 any opportunity to escape, in order to complete our knowledge 

 concerning the form, the dimensions, and the structure of the 

 globules of the blood ; for an exception to a rule, in appear- 

 ance as well established as that relative to the constancy of 

 this form in each of the classes of vertebrated animals, may 

 make us suppose that there are other similar anomalies ; 

 and it is perhaps by means of these exceptions that we will 

 ultimately be able to seize the relations which ought, very 

 probably, to exist between the physical characters of these 

 corpuscles, and other peculiarities of the organization. This 

 is a subject of research which we would recommend to travel- 

 ling physiologists, and to those whose position in large mena- 

 geries allows them to multiply and vary their observations ; 

 for experiments of this natiu'e do not subject the animals sub- 

 mitted to them to any danger, and may give results full of 

 interest to physiology. It would appear to us, above all, import- 

 ant to examine, in this respect, the blood of the Monotremata, 

 Edentata, the Phocse, and the Cetacea, among the mammifera; 

 that of the Crocodiles, the Sirens, and the Axolotls, among 

 the reptiles ; and among the fishes, that of the Bonites, whose 

 temperature, according to Dr J. Davy, approaches that of 

 warm-blooded animals. If, in this list, we omit the Cassowa- 

 ry and the Ostrich, which, of all the birds, are the most ab- 

 normal, it is because your commissioners are already assured 

 that, with relation to the form and dimensions of the globules 

 of the blood, these animals differ in no respect from all those 

 of the same class already observed by micrographers. These 

 corpuscles are really elliptical, and have appeared to us to 

 have, in the Cassowary of Neiv Holland, about igthby jsjd of a 



