PRACTICAL NOTES ON 44 HETEROaENESIS.’ 
347 
and several different diatoms seemed to be produced correspond- 
ing to these initial forms, mm'” (fig. 12). “This,” says Pro- 
fessor Smith, 44 would be wonderful if true ; but not only is 
there no evidence that actual diatoms did come from the 
vesicles of Vccucheria , but any one familiar with the observa- 
tion of living Diatoms can tell where they did come from 
They were in the gathering .... and made their appearance 
out of the debris .... as we know they will do under the 
influence of light But, besides, Diatoms do not groiv 
by increase of size ; there are no such things as broods of young 
frustules The late Dr. Grreville .... fully agreed with 
me in this.” 
44 Further, fig. 13, PI. CXL., is a copy of another illustration 
given in the 4 4 Beginnings of Life.” It is declared to represent 
the 44 resolution of Euglena into diatoms.” It is said concerning 
it that 44 the whole of the contents of an euglena seemed to have 
been resolved into distinctly striated Naviculce .... although 
the earlier stages of the transformation were not seen (!) I 
have no doubt that the diatoms originated in this way.” Upon 
this Professor Smith observes : 44 He (Dr. Bastian) is more easily 
satisfied that a euglena can transform into a diatom, which pos- 
sesses a wonderful silicious and beautifully-sculptured epiderm, 
than he is that bacteria come from air-germs ; ” and then he 
clearly shows that the group of Xaviculse seen in fig. 13 
are simply a group that were devoured, and their protoplasm 
digested, by an amoeba. They constantly are ejected in this 
way from the body of the amoeba after the nutrition has been 
abstracted, and look like an encysted mass with an envelope 
complete; and even when treated with acids, although the 
envelope disappears, the frustules still adhere. And Professor 
Smith has 44 slides as well as material showing this in abundance.” 
All this, it may be presumed, is capable of suggesting two 
things : 1 . The danger of attempting to discover new modes of 
44 genesis ” until we have made ourselves acquainted with the 
old ones ; and 2. That 44 heterogenesis ” is not even a scientific 
hypothesis , for the 44 facts ” on which it is founded have not re- 
ceived scientific investigation. 
But hitherto I have dealt with the question as a whole. I 
may now touch a point with which I have endeavoured to make 
myself specially familiar. Dr. Bastian claims that bacteria are 
constantly being 44 transformed ” into monads. This, it is 
affirmed, takes place in what is known as the 44 proligerous pel- 
licle,” or scum which very rapidly forms on the surface of in- 
fusions. This pellicle is formed chiefly of bacteria ; but it may 
contain every variety of form possible to a given infusion, in the 
earlier stages of their development. It is worthy of remark 
that there is not a single instance throughout in which Dr. 
