Mr. H. J. Carter on Difflugia pyriformis". 251 



down as irl-oth of an inch in Pritchard (p. 553), but mine ave- 

 raged only -cT^th of an inch in length ; yet in April last I found 

 two others in the same place larger than Pritchard^s measure- 

 ment, viz. -TB-oth of an inch long ; so that all three of these 

 DiffiugicE are found together here ; and although the latter, in 

 the few specimens of it which I obtained, did not present the 

 green colour of the two former, yet it is so like them in every 

 other respect, that I cannot help thinking that D. acummata 

 and D. jjroteiformis are but small varieties of D. pyriformis, 

 which is by far the largest in body of all, because the measure- 

 ment assigned to D. acuminata (viz. y^th of an inch) probably 

 includes the diverticulum. Still the Rhizopoda vary so much 

 both in size and form, that the tailed variety may be the largest, 

 and the pyriform one subordinate in size and number, or the 

 subglobose one, and so on, in another locality. In the present 

 instance, however, it is D. acuminata and D. proteiformis which 

 are so very subordinate in size and number. The absence of 

 the green colour in D. proteiformis may have taken place in the 

 process of generation, as it will hereafter be shown to do in D. 

 pyriformis; at the same time, if future evidence should prove 

 that it is never green, then it will be necessary to regard D. 

 proteiformis as a different species ; for the green colour in D. 

 pyriformis and D. acuminata is due to the presence of chloro- 

 phyll-cells, as much as the green colour in the body of Hydra 

 viridis. ' 



Of the 200 specimens of D. pyrifoj^mis mentioned, there were 

 eighteen colourless ones, owing, as just stated, to the total ab- 

 sence of chlorophyll-cells, which appears to indicate the stage in 

 the generative process to which I have just alluded. 



There were also fourteen empty tests (and I have found many 

 more since, with a less number of filled ones), which may have 

 arisen from their contents having left them during the process 

 of conjugation, or, in a more advanced stage of the genera- 

 tive process, from the old animal having become effete, and 

 the new generation having left the test, or from the death of 

 the animal accidentally. The number, however, is so much out 

 of proportion to the filled tests, both green and colourless, that 

 it stands much against the possibility of the conjugation being 

 exactly like that of Spirogyra, i. e. of the result of this conjuga- 

 tion being always to leave one cell empty. 



All my specimens were collected from the same place where I 

 found Amoeba princeps in April last (see Annals, vol. xii. p. 30, 

 1863), and in the following way, viz. by taking up the surface 

 of the bottom of the little pools of water among the dead leaves 

 with an india-rubber bottle and tube, and transferring it to a 

 glass bottle, then taking out the sediment by portions with a 



17* 



