322 Dr. F. Cohn on a new geinis of the family 0/ Volvocinese. 



celebrated illustrations of the Infusoria ; this gentleman had re- 

 garded the moving globules as a new Infusorium, wftiich he called 

 the wreath-animalcule ; Dr. Frantzius, on the other hand, looked 

 upon it as a microscopic Alga which must form the foundation 

 of a new genus (see Frantzius's Naturhistorische Reiseskizzen 

 aus dem Salzkammergut und Tyrol, Siebold and Kolliker's 

 Zeitschrift f. wiss. Zoologie, iii. part 3). 



So much the pleasanter was my surprise in finding a large 

 quantity of the elegant wreath-animalcules in a living condition, a 

 few days after I received the above information. I had taken 

 advantage of the Whitsuntide holidays of the past year (1851) 

 to explore our Silesian highlands, and used that opportunity of 

 seeking out the granite block, almost classic in the history of mi- 

 croscopic organisms, on which our first German lichenologist. 

 Major von Flotow of Hirschberg, discovered his Hcematococcus 

 pluvialis, ten years ago. Through the friendly instructions of 

 this distinguished naturalist I soon succeeded in finding the 

 stone, which forms a bridge across a ditch in the neighbourhood 

 of Hirschberg : lying in the path between the village of Grunau 

 and its church, this stone has in the course of time been so worn 

 away by the number of church-goers, that it now presents a 

 large irregular hollow; in this the rain-water collects, which, 

 like the stone itself, is inhabited by millions of Chlamydococcus- 

 globules. When, however, I collected water from this place my- 

 self on the 17th of June, to my amazement I found, scattered 

 individuals of the Chlamydococcus pluvialis indeed, but a far 

 greater quantity of the inseparable companion of the Chlamydo- 

 coccus, the beautiful rose-red Rotifer Philodina roseola, which 

 always occurs with the red Chlamydococcus-^ohvXe,^ in Silesia, at 

 Liege and Giessen, in the lake of Neufchatel, and even in the 

 eternal snow ; and moreover I at the same time detected in the 

 water numerous specimens of that elegant wreath-animalcule 

 with which I had already made acqiiaintance from the sketches 

 of Dr. von Frantzius. Major von Flotow informed me, at the same 

 time, that he had seen this remarkable form as long ago as the 

 end of June in the year 1846, and had applied to Ehrenberg 

 respecting it, but had not received any answer from him. I 

 brought home to Breslau a bottle of rain-water from this granite 

 block, for the purpose of further investigation, and this furnished 

 me abundant material for the following researches. 



I. Organization. 

 The organisms I am now about to describe exhibit an extra- 

 ordinary variety of size and shape, but they are all essentially of 

 similar structure, and consist, as already mentioned, of eight green 

 spherical corpuscles having their central points situated at the cir- 



