404 PEOr. ALLMAN ON 'IHE EECENT KESEAKCHES 



Dujardin (fig. 7), one of the finest of the freshwater Monothalamia, 

 and has determined the time which intervenes between each 

 systole. He has found that, at a temperature of 16° Eeaumur, this 

 was almost exactly 90 seconds. The pulsation was of that kind 

 which is general among the Ehizopoda, a rapid contraction fol- 

 lowed by a gradual accumulation of a clear liquid in the same 

 place until the vacuole becomes once more completely filled, then 

 another sudden collapse, and so on. 



Hertwig and Lesser have made some further interesting obser- 

 vations on EuglypJia alveolata. They have observed in it the 

 structures which Carter calls " granuliferous cells," and which 

 he believes to be produced by the division of the nucleolus, and 

 to be connected with the formation of spermatozoids. Hertwig 

 and Lesser, however, have been unable to assert any thing re- 

 garding the economy of these '''granuliferous cells." They are 

 roundish vesicle-like bodies irregularly scattered through the pro- 

 toplasm outside of the nucleus, and more or less filled with small 

 round bluish granules, which mostly appear arranged in regular 

 concentric circles. They show a great resistance to concentrated 

 acetic acid, a fact which is scarcely consistent with their deriva- 

 tion from the nucleolus ; and when present they are usually in 

 considerable number, without either the nucleus or the nucleolus 

 having disappeared. 



EuglypJia alveolata is remarkable for the rich development of its 

 pseudopodia, and for the frequency of their subdivision. They 

 mostly spring from broad-lobed homogeneous processes of the 

 protoplasm. 



Within the shell of Euglypha alveolata may often be seen de- 

 tached plates resembling in size and form those of the shell itself. 

 They have been noticed by difi"erent observers, but more especi- 

 ally by Hertwig and Lesser and by F. E. Schulze. In individuals 

 in which the living protoplasm is still included, they lie upon its 

 surface in a layer parallel to the shell-walls. They are probably 

 destined for the building up of a new shell after the shedding of 

 the old one, or, as Hertwig and Lesser suggest, may be connected 

 with the formation of the inner shell in the peculiar encysting 

 process which they have studied in this rhizopod. Similar 

 plates have also been found by Hertwig and Lesser in the E. am- 

 pulacea, Dujardin. 



The encysting process (fig. 7) which Hertwig and Lesser have 

 studied in H. alveolata, and which had been previously noticed by 



