
LIFE-HISTORIES AND THEIR LESSONS. 199 

or insect, however small, “transmuting.” The explanation is easy. 
Whenever we know the history of a living form, although we know 
that in the process of ages it may slowly change, and give rise not 
only to varieties but to different “species” and genera, yet that its 
metamorphoses or developmental processes, as capable of observa- 
tion in the life-time of a man, or a generation, will be as certain as 
the reactions of a metal or an acid. 
The strange position taken up by Dr. Bastian, in his Beginnings 
of Life, has warped and rendered futile the character and results 
of the work of more than one earnest worker, desirous of using a 
microscope in the interests of Biological Science in this city, during 
the past few years. Many may contribute facts who may not be 
masters of the doctrines of a science, at least in microscopical work. 
But when their judgments are warped by the affirmation by an 
apparent “authority,” that they are to expect to find Heterogenesis, 
which is “defined” as “the origination of living beings more or 
less complex in organisation from other living units, wholly diffe- 
rent from themselves, and having no tendency to assume or revert 
to the parental type.” * 
This is, in brief, a sort of charter for the wholesale ‘explanation ” 
of what we do not understand in the development of living forms, 
into a “fact” for Heterogenesis. ‘There are caterpillars of large 
size that are found sometimes in England, but often in America, 
which are the “hosts” of scores of minute larve, which eat and 
grow upon the fat and non-vital parts of the host; in the majority 
of cases they at last attack the vital organs, kill the caterpillar, and 
then eating their way through the skin, as in Plate III., Fig. 9, and 
then weaving cocoons on the surface of their larval host, wait until 
they emerge from these as perfect flies. ‘They do not, however, 
always kill their unwilling entertainer. Fig. 9 @ is from a drawing, 
by an American observer, of the cocoons empty ; and Fig. 9 bisa 
magnified cocoon, 
Now, to deceive in this case is scarcely likely; we know, by the 
aid of popular literature, and in some instances of school boards, 
that this is the work of an Ichneumon fly. But a similar case 
amongst unknown microscopic forms might easily be translated 
into “ palpable Heterogenesis.” 
Not less remarkable, as a suggestive illustration, is that terrible 
internal scourge of man himself, Z7ichina spiralis, Every muscle 
of the body of a trichinised man or animal may be literally crowded 
with the delicate coiled “ worm” at rest in its cyst. Ifwe did not 
know that it had a history which, happily, is more or less com- 
pletely compassed, could the thoughtful and practised Biologist 
conclude that it was the result of the direct transformation of the 

* Beginnings of Life, vol, i, p. 244+ 
