i 



> 



Miscellaneous. 459 



The larva of Cunina is a hydra, with the power of asexual multi- 

 plication ; but instead of giving rise to medusa-buds like an ordinary 

 hydroid, it becomes directly converted into a medusa by a process 

 of metamorphosis ; it is a true larva and not an asexual generation, 

 although the occurrence of asexual reproduction renders tho gap 



between this form of development and true alternation very slight 

 indeed. 



In Cunina we have a series of this kind : 



Egg, 



I 

 Larva — Larva — Larva, 



I I I 



Adult Adult Adult. 



If tho larva which is produced from the egg were to remain per- 

 manently in the hydra stage, we should have a scries like this : 



I 



Hydra — Hydra — Hydra, 



1 i 



Medusa Medusa ; 



and such a history would bo a true alternation. — Johns Hopkins 

 University Circulars, April 1883, p. 73. 



Ophryocystis Biitschlii. By M. A. Schxeider. 



I have discovered in the Malpighian vessels of Btaps a most 

 curious new sporozoarium. It has the form and external appear- 

 ance of an Amoeba ; its body is often covered with simple or divided 

 digitiform processes, which may equal or exceed the central mass 

 in length. The latter, which is charged with granules, contains 

 from one to ten spherical nuclei 3 p in diameter, with one or two 

 punctiform nucleoli. 



The multiplication of the species is effected principally by cysts. 

 Encystment takes place only between individuals with a single 

 nucleus and of spherical form. The two conjugated organisms 

 secrete around them successively several envelopes, each marked with 

 an equatorial line of dehiscence. 



The phenomena which succeed one another in the cyst arc very 

 peculiar. Each of the two nuclei divides so as to produce three 

 nuclei in the correspondiug half of the cyst. Of the six nuclei thus 

 produced, only two take part in the constitution of the reproductive 

 elements, represented exceptionally by two small spores, and nor- 

 mally by a single large spore. A portion of the plasma of the cyst 

 is implicated with the nuclei in this spore-formation. The four 

 other nuclei and the rest of the granular mass of the cyst remain 

 unused and become liquefied. The spore, resembling a Xavieula, 

 produces in its interior, besides a residuary nucleus, a certain num- 

 ber of falciform corpuscles, each provided with a nucleus.— Carnptes 

 Rendus, May 7, 1883, p. 1378. 







