1(S 
and Dallinger are now experimenting on the effects of heat on 
the fully developed form, and also on the germs, from which it 
seems that while the former are destroyed by a moderate heat, the 
latter can resist a high temperature. The result of these experi- 
ments have just been published, and it appears that while the form 
which gave birth to minute living organisms were scarcely able to 
survive a temperature of 82-22 c. (nearly 180 Fahrenheit,) the 
sporules withstood a temperature of 148-88 c. (or nearly 300 Fah.) 
Ihe study of these minute and apparently lowly organized forms, 
appears to me to be highly necessary for the determination of the 
truth or error of Darwinism; and as far as my very limited 
researches have gone, the evidence derived from such study is not 
in favour of the Darwinian hypothesis. There appears as much 
persistancy of type in the monad above alluded to as in the 
highest forms of life. We do not find them developing into 
Kotifers or Tardigrada, any more than we find a sheep developing 
into a greyhound. I shall perhaps be reminded, that in the latter 
case I have overlooked one very important element — viz., time, and 
therefore no change could possibly he discernible during the life- 
time of an observer. Ihis objection would, however, hardly apply 
to the monads, of which something like 180 generations would be 
produced in the course of one year. Now if a series of observa- 
tions are extended over three years, 540 generations would have 
been produced ; this would be equivalent to many thousand 
years of production in the higher orders of mammalia. I might 
cite many similar examples if time permitted, I must, however, 
- call jmur attention to those remarkable forms of vegetable life 
— the Diatomaceas ; they made their first appearance as late as the 
Miocene epoch, and then they occur in enormous quantities, but we 
have no trace of any earlier analogous form from which they could 
have been developed. Eecent observations also tend to show that 
in all probability no form had become extinct or even altered. The 
keenest observer could not detect a difference between a fossil 
diatom, provided it was uninjured, and one that was living yester- 
day. No trace of development into other or more complex 
organisms has ever been detected, although we have the advantage 
