12 MORPHOLOGIC VARIATION 



ferred to new media will answer this question of viability. None 

 of the authors has followed the first procedure; Mellon has used 

 the second in a few instances, and as has been mentioned above, Gard- 

 ner, Hort, and Almquist have followed the third in the case of bud- 

 ding and branching cells. 



Hort states that an involution form is, "strictly speaking, a sterile 

 organism which is not only incapable of maintaining its reproductive 

 activity, but is also incapable of maintaining its integrity of form" 

 (1920, p. 370). Whatever may be the dictionary definition of the 

 word, this idea is erroneous, for senescence and death are processes 

 requiring some time and the terms are relative. It may well be 

 that an injurious agent or process has led to the deformity of a cell 

 long before it has actually been killed, and that such a cell, an in- 

 volution form in the sense that it has undergone a modification of 

 form as part of a degenerative process, is still capable of "reviving" 

 and multiplying when transferred to a more favorable environment. 

 Even the proof of viability of single variant cells does not, therefore, 

 prove that their variation is not the result of a degenerative process. 



Throughout these works is the assumption that bacteria possess 

 discrete nuclei; and Almquist, Mellon, and Enderlein have definitely 

 interpreted structures which they have seen as nuclei. It would take 

 too much space to debate here this much disputed question 

 concerning the presence or absence of nuclei in bacteria, but I feel 

 safe in stating that no one has so far demonstrated certainly that 

 any of the true bacteria possess a discrete nucleus. The structures 

 described by Meyer and Paravicini are the only ones that have been 

 reported which fulfill the requirements of a nucleus, but their find- 

 ings have not been confirmed by anyone except in the case of endo- 

 spore-forming bacteria during the stage of spore formation. The 

 assumption that bacteria possess nuclei is therefore unwarranted, and 

 the casual way in which this or that intracellular structure is desig- 

 nated a nucleus without any clear evidence is characteristic of all 

 of the data. Almquist mentions no attempt to differentiate his nu- 

 clei from volutin, neither does Mellon, though Meyer has clearly 

 pointed out the danger of mistaking this material for chromatin and 

 the means of differentiating it. Mellon lays stress on the skein-like 

 structure as evidence of a nuclear nature, but this structure may be 



