244 



Prof. H. C. Bastian on Hetero genetic 



[Mar. 21, 



and not others, seems quite impossible to say. One can only assert the 

 fact, and add that these highly refractive ovoid corpuscles were, for the 

 most part, more prone to produce Fungus-germs than Monads. Many of 

 them soon grew out into dissepimented fungus-filaments, which rapidly as- 

 sumed the Penicillium mode of growth. The spores, which were abun- 

 dantly produced in terminal chaplet-like series, were, however, small, ho- 

 mogeneous, spherical, and colourless. 



On several occasions I have seen Monads produced in this way, by direct 

 and immediate separation from the pellicle ; though, as M. Pineau had 

 stated, on other occasions they may be seen to arise in groups, in which 

 they first appear as aggregations of motionless corpuscles. The solitary 

 mode of origin is that which has been described by M. Pouchet ; and al- 

 though the details given by him are not very full, so far as they go they 

 are in accordance with my own observations. M. Pouchet, for instance, 

 describes the flagellum as being closely applied to the body, and motionless 

 for a time. This I have also found to be the case. I have, moreover, on 

 one or two occasions, been able to watch all the transitions from the mere 

 motionless corpuscle to the flagellated Monad; just as, on other occasions, 

 I have watched almost similar corpuscles develope into Fungus-germs. 



Sometimes the flagellum is seen attached to corpuscles which still dis- 

 play almost unaltered Bacteria imbedded in their substance : generally, 

 however, the corpuscles which separate from the pellicle in this compara- 

 tively unaltered condition, undergo certain slow changes before the flagellum 

 is developed. The contained Bacteria become more and more indistinct, 

 whilst the general substance of the corpuscle becomes rather more refrac- 

 tive, so as to produce ordinary protoplasm. Corpuscles about -^woo" in 

 diameter are often very obscurely granular and quite motionless. They 

 grow, however, and when they have attained the size of 4-5W" * Q diameter 

 they frequently begin to exhibit slow undulating alterations in outline, and 

 tend to assume an ellipsoidal form. One specimen, 3 3 X 6 " in diameter, was 

 seen without a flagellum, but slowly alternating between the spherical and 

 ellipsoidal forms. Suddenly, at one extremity of the ellipsoid, a series of 

 rapid contractions and protrusions of its substance were observed, and when 

 they ceased, a motionless filament was seen bent around one side of the 

 body. Three minutes afterwards a vacuole appeared for the first time at 

 the opposite extremity of the ellipsoid. The corpuscle remained almost 

 motionless for twenty-five minutes, merely exhibiting very slight changes 

 in outline ; after thirty minutes the first slow bendings of the flagellum were 

 seen ; and after thirty-five minutes the whole organism began to exhibit 

 slow semi-rotations, at intervals of a minute or two. After forty minutes the 

 movements were pronounced and of a starting character, dependent upon 

 sudden contractions of portions of the body of the organism rather than 

 upon movements of its flagellum. After fifty -five minutes, the corpuscle 

 unfortunately became hidden, owing to its having floated underneath a 

 portion of the pellicle. How far the rapidity of the evolution of the 



