ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 583 



Limulus is a convenient animal in which to study coagulation, on 

 account of the great quantity of blood contained. On exposure to air 

 it coagulates, though not firmly, in a few minutes. Dr. Howell was 

 unable to prevent coagulation by saturation with magnesium sulphate, 

 which Halliburton found possible. Four different albumens were found, 

 coagulating at 60° C, 70° C, 75° C, and 80° C. The last is 

 especially difficult to precipitate completely. The author differs 

 from Halliburton in regarding the name haemocyanin as more 

 applicable to this last albumen. From the various experiments on 

 the serum the author concludes that the albumens of Limulus serum 

 belong to the globulin group, and though not identical with para- 

 globulin, it is to it that they approach most nearly. Hfemocyanin, 

 a combination of copper with proteid, gives no absorption bands, 

 though it cuts off a large portion of the blue rays. When oxygen is 

 excluded it loses colour ; this is well seen in the blood of Crustacea ; 

 but in Limulus the result is not so evident ; the respiratory process 

 seems less marked. The loss of colour only commences when the 

 last albumen begins to be thrown down. Coagulation is caused by 

 the union of processes sent out by the corpuscles ; these processes 

 shorten and draw the corpuscles closer together. The fibrin thus 

 formed resembles that of mammalian blood, by its solubility in lU per 

 cent, magnesium sulphate. 



In Callinectes the coagulation of the blood when drawn is much 

 less rapid than in Limulus ; moreover a firm jelly is formed. There 

 are only two albumens, coagulating at 55° C. and 68° C, the latter 

 of which is haemocyanin. The blue colour of the blood disappears 

 on the passage of C0 2 ; and the author considers, from various experi- 

 ments, that the haarnocyanin in the two animals is a different substance. 

 The albumens appear to be globulins. The coagulation arises in the 

 same general way as in Limulus, but the fibrin produced has different 

 properties. Dr. Howell concludes from the examination of the blood 

 in these two animals that " the differences are too wide to permit us 

 to suppose any close relationship between the two forms ; " but 

 observations on the blood of arachnids are necessary before concluding 

 anything as to the relation of Limulus to them. 



In the perivisceral fluid of a Holothurian — Thyonella — oval, 

 nucleated, hasmoglobinous corpuscles are found, as well as colourless 

 amoeboid corpuscles. These corpuscles sink and form a sort of 

 incipient coagulation, caused by the fusion of thick pseudopodia of the 

 white corpuscles, as well as of the corpuscles themselves ; the red 

 corpuscles do not fuse, but may get entrapped in the mass. No 

 albumens were found in this serum. 



Mollusca. 



Embryology of Gastropods.* — Mr. J. P. MacMurrich gives a 

 preliminary account of his work on the development of some marine 

 Prosobranchs. 



Out of the numerous eggs deposited by Fasciolaria lulipa, in each 



* Johns-Hopkins Univ. Circ, v. (1886) pp. 85-6. 



