CONTRIBUTIONS TO THE CYTOLOGY OF THE BACTERIA. 419 



1. Coccus Forms. 



Cocci of various sizes are very common in tlie large in- 

 testines of many different animals. Unfortnnately, however, 

 they are usually of very small size, and hence exceedingly 

 difficult to study accurately. I have examined many cocci 

 from the large intestines of frogs and toads (Rana tempo- 

 raria, R. esculenta, Bufo vulgaris), of newts (Triton 

 vulgaris), of cockroaches (Periplaneta americana and 

 Stylopyga orientalis) and of several different snakes. All 

 these have proved to be of little value, because the organ- 

 isms were usually so small that I could not be certain of their 

 structure as seen under the microscope. The living- oro'auisms 

 were usually very refractile, and showed no internal sti-ucture 

 which could be definitely separated from appearances due to 

 optical phenomena. For instance in a small Micrococcus — 

 examined under a high power — a dark spot of varying size 

 <3an often be distinctly seen in the centre of the organism.^ 

 This is not, I believe, a definite body — such as a nucleus — 

 lying in the cell, but is merely an appearance caused by optical 

 phenomena connected with the microscope. 



( A ) !M i c r o c o c c i . 



Onlv two Micrococci of suitable size for investig-ation 

 have come under my notice, but they have both revealed a 

 structure which is quite unmistakable. Both forms were 

 found in the large intestines of lizards — Lacerta muralis 

 ^nd Mabuia carinata. 



Micrococci from Lacerta muralis. 



The lizards were obtained in the neighbourhood of Xaples. 

 I found that nearly all of them harboured a large Micro- 

 coccus in greater or less numbers. 



' These ai^ijearances i)robal>ly led Schottelius (1888) to helieve that 

 he could see a nucleus hi livina- Bacteria. 



