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might, indeed, be merely a phase in the life development of 
the “ curious fungoid growth ” itself. All these possibilities, 
and a hundred others, in every instance should he most crucially 
considered before the semblance of a case for “ heterogenesis ” 
could even be presented in a strictly scientific form. 
But Dr. Bastian has neglected such precautions, and has 
adopted the observations of others, which are even more in- 
valid. How serious the resulting errors are, in only one 
direction, has been plainly shown by Professor H. L. Smith,* 
of America, whose competence to write critically on the sub- 
ject of diatomaceae will not be disputed. He has given an 
absolutely destructive detailed criticism of every important 
instance of the reputed transmutation of something else into 
diatoms which Dr. Bastian has presented, and brings out 
clearly the mistake of attempting to infer the “ heterogenetic ” 
origin of vital forms of whose ascertained history the observer 
was ignorant. Professor Smith says : “ I have probably witnessed 
more of the phenomena of conjugation and growth than any 
other person, and can affirm, without fear of being disproved, 
that .... any kind of transformation of Pediastrese or Desmids 
into Diatoms never has happened — nay more, never will happen.” 
“ I look,” he continues, “ more particulary to the evolution of 
diatoms, fully convinced, however, that the errors of misinterpret- 
ing what he (Dr. Bastian) saw are quite as great with the desmids 
as with the diatoms.” For example, fig. 12, PI. CXXXIX., is a 
reproduction of one of Dr. Bastian’s figures, which he declares 
represents, at e, e', the “ heterogenetic ” origin of diatoms from 
the Gladajphora filament a. Professor Smith says, poor as the 
cut is, we easily recognise the “pedunculated diatoms” as 
“ Acanthes exilis in its normal condition /” In fact, it con- 
stantly grows naturally thus on Cladophora , Vaucheria and other 
algae. But because Dr. Bastian was not aivare of this , he took 
the observation as a fine illustration — which in view of the facts 
we have no objection to admit — of heterogenesis. Whereas, “ if 
it had been allowed to live it would have continued the process 
of self-division until finally .... a new sporangium would 
have formed the commencement of a new series.” 
Again, Dr. Bastian affirms the small forms figured at IV 
(fig. 1 2) are algoid vesicles budded off from Vaucheria, and that 
they “ gradually become converted into different kinds of dia- 
toms.” And further, “ These bodies increased in size, and it soon 
became obvious that they were young Naviculce (IV); the exact 
pattern assumed in the early stages is subject to much variation, 
* Vide “Archebiosis and Heterogenesis,” the “Lens,” Jan. 1873; and 
“Quarterly Journ. Micro. Science,” vol. xiii. p. 357 ( '; and note by Mr. Archer, 
ibid. p. 313. 
