306 Miscellaneotcs. 



As for the third mass which was formed within the sporoblast, it 

 is destined to furnish the plasma of the spore ; at a very early stage 

 we find in it two nuclei generally close together, which persist until 

 maturity. Now did these two nuclei preexist within the sporoblast, 

 which in that case would primarily contain four of them, or do they 

 result from the division of a single nucleus, as must be the case if 

 we admit with Biitschli that the sporoblast contains three nuclei 

 only ? This is the point which my observations have not enabled 

 me to determine. 



Up to this point the spores are rounded or oblong ; they lose no 

 time in assuming their final shape by surrounding themselves with 

 an envelope, the origin of which has unfortunately escaped me. In 

 the tailed spores the tail is at first bent back on one side of the 

 spore, and remains in this position until the rupture of the envelope 

 of the primitive sphere, which persists for a tolerably long time. 



It is not unusual, especially in the tench, to meet with spores 

 with from three to eight capsules. I have always found a nucleus 

 corresponding with each one of these ; their formation therefore 

 probably takes place in the usual way. In this case the sporoblast 

 must without doubt have contained an abnormal number of nuclei ; 

 sometimes indeed it seems probable that a single spore is formed at 

 the expense of the primitive sphere. 



In conclusion, we may sum up the chief results of my investiga- 

 tions as follows : — 



1. The nucleus of Myxosporidia divides by karyohinesis. 



2. The polar capsules are formed at the expense of little masses 

 of plasma, which are difterentiatcd within the sporoblast and contain 

 a nucleus ; the process of their formation presents many points of 

 analogy with that which has been observed by Bedot * in the nema- 

 toblasts of species of Velella and Physalia. 



3. The plasmic mass of the spore is derived from another portion 

 of the sporoblast ; it contains two nuclei and a vacuole with contents 

 staiuable reddish brown by iodine, the existence of which I have 

 already described, and the presence or absence of which is constant 

 in the same form,' — Comptes liendus, cxi. (Nov. 1890), pp. 692-695. 



On the Sense of Smell in Starfish. By M. Henei Prouho. 



It is a legitimate conclusion from our knowledge of the anatomy 

 of Starfish that the sense of sight is not suflflciently developed in 

 these animals to enable them to distinguish and come up with their 

 prey, and we are naturally led to admit that the sense of smell is 

 their sole guide in the search for food. Nevertheless I have thought 

 it worth while to render our knowledge of this subject more certain, 

 by means of a few experiments directed towards the following 

 points : — (1) observing how the behaviour of a Starfish is affected 

 by the conditions under which prey is off'ered to it ; (2) demon- 

 strating the uselessness of the organ of Aision in the search for 

 food ; (3) determining whether the sense of smell is diftused or 



* Bedot, " Kecherches sur les cellules urticantes," Rccueil zoologiciue 

 Suisse, 1888. 



