ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 403 



and finally seen to attach the top of its flagellum to the glass, and 

 revolve swiftly for a few moments, when instantly the whole body 

 became spherical, rays were shot out, and the transformed monad was 

 in no point, except that of size, to be distinguished from its Actino- 

 |9i^j-i^s-like cousin. The whole development, from the time when the 

 monad began its free life, occupied two hours and some seconds. 



This mode of reproduction secures a more widespread distribution 

 of the young than would be possible did they depend on the sluggish 

 Actinophrys form. It seems reasonable to suppose that this is a wise 

 provision for the perpetuation of the species should adverse condi- 

 tions of life arise and also to prevent an undue accumulation of the 

 animals within a circumscribed space. 



Aberrant Sporozoon.* — J. Kunstler describes an aberrant sporo- 

 zoon for which he suggests no name. It is a kind of monocystid 

 Gregarine, found in the body-cavity of Periplaneta americana. It is 

 at first placed to the Jexterior of the epithelial cells of the mid- 

 intestine, in front of the insertion of the Malpighian tubules. It 

 grows in the cell, crosses the muscular tissues, and drives before it 

 the peritoneal investment; the sac thus formed becomes stalked. 

 The Gregarine, after further growth, breaks through the peduncle and 

 escapes into the body-cavity. At first it consisted merely of a single 

 cell with a central nucleus ; later on it consisted of two similar bodies, 

 so that it appeared like a pair of conjugated monocystids ; here, how- 

 ever, there has been no conjugation, for the nucleus was often seen to 

 be elongated and more or less constricted in its middle, as if it were 

 about to divide. Sometimes there are three lobes. The adult exhi- 

 bits no movement of translation, and only feeble contractions result 

 from the application of acids. The adult has, when encysted, two 

 envelopes ; before encystation it becomes transparent, whereas all 

 other forms are opaque. 



Noetiliieidse.t — F. Eitter v. Stein in Pt. III. of his ' Infusions- 

 thiere,' gives some new interesting facts respecting Noctiluca miliaris 

 and other allied forms. This Infusorian is unusually large, some- 

 times having a diameter of 1 mm. ; although spherical in shape a dorsal 

 and ventral surface may be recognized, as Donitz first pointed out, by 

 the presence of a rod-like structure (stahplatte) which lies in the 

 outer membrane ; this body has a shovel-like flattened anterior end 

 and lies on the ventral side of the mouth. The tentacle is supported 

 by two skeletal pieces, and is not apparently a sensory organ as has 

 been thought, but assists in bringing food to the mouth. The pro- 

 toplasm of the body is not uniformly distributed but lies in a mass 

 between the mouth and the stahplatte sending out branched proto- 

 plasmic filaments which are attached to the outer membrane. Closely 

 allied to Noctiluca is the genus Ptychodiscus which has, however, a 

 simpler organization. The body is inclosed by two thick-walled shells 

 of parchment-like consistency united along their margin by a more 

 delicate membrane ; the dorsal shell is distinguished from the ventral 



* Comptes Renrlus, xcviii. (1884) pp. 633-4. 



t ' Organisraus der Infusiousthiere/ Abth. iii. Halfte ii. 



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