ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 987 



second objection is that the theory attributes the function of contraction to 

 the network which forms much less of the bulk of the fibre than does the 

 sarcous substance ; but the latter may have to perform thermogenic 

 functions which must absorb a far greater amount of its energy than does 

 the contractile function. 



Comparative Size of Blood-corpuscles in Man and Domestic Animals.* 

 — Miss F. Detmers considers that she has established, by a series of 

 measurements, that there can be no question but that the blood of human 

 beings can readily be distinguished from that of such animals as the mule, 

 cat, calf, and horse, and more readily from cattle, sheep, and pigs. 



Blood-corpuscles of the Cyclostomata.f — Prof. D'Arcy W. Thompson 

 traverses the generalization found in many text-books that the red blood- 

 corpuscles of Cyclostomata are round and not oval. He finds, as indeed 

 did J. Midler, that the red corpuscles of Myxine are large and oval, being 

 •025- -028 mm. in length, about -01 mm. in breadth, and about -003 mm. 

 in thickness. In Petromi/zon marinus, the red blood-corpuscles are circular, 

 and about "OlS to '014 mm. in diameter, and the nuclei are excentric and 

 stain very slowly and feebly with magenta, whereas in Myxine they are 

 central and stain easily. Shipley, who has recently stated that the red 

 corpuscles of the ammocoete are oval, confirms his statement ; this note- 

 worthy difference between the larval and adult forms recalls the differences 

 in the red corpuscles of the tadpole and the frog. 



The white blood-corpuscles of Myxine are nearly or sometimes quite as 

 numerous as the red, are of about the same size as in man, and have a very 

 large granular nucleus. In P. marinus they are three or four times as 

 numerous as the red, their nuclei are small and stain well ; forms transi- 

 tional in shape and size to the red corpuscles may be recognized. 



Hsematocytes.^ — M. Fokker gives a somewhat astounding account of 

 some observations on the behaviour of blood. He has previously sought to 

 show that protoplasm from a healthy organism, placed in a nutritive 

 medium, with the exclusion of microbes, may remain alive and cause 

 fermentations. He now seeks to prove that such protoplasm may develope 

 a vegetative form, different from that exhibited in the body of the animal 

 from which it was taken. 



Some blood was taken with all necessary precautions from a healthy 

 animal, placed in distilled sterilized water, and kept at the ordinary 

 temperature, and at 37° C. It remained alive, but above 37° died. 



If the distilled water be replaced by a very weak solution of nutritive 

 salts, or even by drinking water, the blood remains at the ordinary 

 temperature alive, for a year even. But at 37°, and above, a sediment is 

 formed. The amorphous molecules in the debris increase gradually and 

 form small vesicles which may attain the dimensions of the blood-corpuscles ! 

 These little knobs M. Fokker calls haematocytes, and the process is 

 designated heterogenesis. These vesicles have nothing in common with 

 any elements previously described in the blood. They may be stained 

 with iodine, or with methyl- violet, fuchsine, and eosin. They have often 

 a regular form, and their size is very variable. They do not multiply in 

 cultures. 



That they are really alive is demonstrated by their growth as observed 

 under the Microscope, and by the fact that they do not develope in the 

 absence of oxygen. 



* St. Louis Med. and Surg. Journ., liii. (1887) pp. 209-15. 

 t Anu. and Mag. Nat. ffist., xx. (1887) pp. 231-3. 

 X Comptes Kendus, cv. (1887) pp. 353-6. 



