* 



Dr. A. Gruber on Protozoa. 267 



which has done me excellent service. This, as is well known, 

 consists in killing the animals quickly by means of a reagent 

 which is allowed to flow under the covering-glass, and which 

 at the same time hardens them, after which, while still under 

 the glass cover, they may be stained, deprived of water, and 

 mounted in Canada balsam. For killing the animals Korschelt 

 employed chromic acid ; but other reagents which produce 

 a rapid stiffening will serve equally well, such, for example, 

 as absolute alcohol, hot solution of corrosive sublimate, 

 I and osmic acid. Landsberg* has recently recommended 



another method, namely the isolation of the Protozoans 



by means of a pipette, which is certainly preferable when we 



have to do only with the making of neat preparations for a 



V collection, but of course cannot be employed in all those cases 



i in which the object under treatment must be preserved in 



situ and at a particular moment, or when it is so small that 

 it could not be detected in a watch-glass by means of low 

 powers. 



I. New Rhizopoda. 



1. Pachymyxa hystrix. 



I had long ago observed, in the coating formed by Diatoms, 

 Oscillarise, and other low plants on the walls of our small 

 marine aquarium [at Freiburg i. B.], certain peculiar roundish 

 bodies, which I at first regarded as the feces of some worm 

 or crustacean. On closer examination, however, there ap- 

 peared to be too great a regularity in their formation, and 

 especially in their external covering ; so that I was led to 

 suppose that these bodies were independent organisms ; but of 

 what kind I was quite uncertain, as no motory phenomena 

 seemed to be observable. After many fruitless endeavours, 

 however, I at last succeeded, by leaving the bodies in ques- 

 tion for a long time undisturbed under the glass cover, in 

 arriving at a conclusion as to their nature and ascertaining that 

 I had before me Khizopods, certainly of very peculiar organi- 

 zation. 



I have not been able to discover in literature any species 

 agreeing with this form, and must therefore create a new 

 name for it. This will be an expression of the bodily consti- 

 tution of the Khizopod, namely Pachymyxa hystrix. 



To the naked eye the larger examples of Pachymyxa appear 

 as small white granules, which stand out very distinctly from 

 a dark ground. In the coat of algae growing in the aquarium 



* " Ueber Konservirung von Protozoen," Zool. Anzeiger, no. 144. 



