36 Br. Beck, Pathological Evolution. [May 27, 



of Darwia's great work, lie has devoted study to this group of plants, 

 and this is what he says : 



"That the blackberries do in fact very frequently produce hybrids 

 is certain. Rubus Coesius a well-known variety of the plant fertilises 

 all other species with which it occui's va common, and like various 

 other species is accompanied by its hybrid progeny. 



"It has often been doubted whether permanent species can arise 

 from hybrids. 



" Hybrids between species mutually remote from each other are 

 often sparingly fruitful. But ^\-e often find, e.g., in Rubus Coesius, and 

 R. Tomentosus (two well-known species of blackberry), in favourable 

 localities, all intermediate links between sterile and fairly fruitful 

 specimens. The original lack of permanence in hybrids, as numerous 

 observations prove, loses itself often entirely in successive generations P 



He further on adds : " If we consider that the majority of our cul- 

 tivated plants have been produced by crossing, whilst all our art and 

 all our exaggerated influences of soil and climate have not been able 

 to affect much change in given natural species, we shall not be able to 

 resist the conviction that the crossing of species and races has a greater 

 effect in the formation of new species than has hitherto been credited." 



Now, I have quoted the above simply to show that the whole ques- 

 tion of " Origin of Species " is still on debatable ground. That being 

 so, surely De Quatrefages has fallen into error, when, instead of 

 beginning his study with the lowest of organisms, he goes to the other 

 extreme, and studies the " highest" for proof of his position. 



Now it would be manifestly rash to jump to a positive conclusion 

 with regard to at present an insufficiently proved assumption, the 

 origin of one species from another, but this I do submit, that in a 

 study of disease phenomena, and in a close observation of the behaviour 

 of the low organisms associated with them, lies a possibility of a solu- 

 tion of this difficult question which is not properly appreciated, and 

 the proud possibility rests with students of the conditions of life of 

 these low organisms, in other words, with students of "Modern Patho- 

 logy," to supply the links wanting in the admirable chain woven by 

 Darwin and other great workers on his lines. 



In this lies the value of the work, and in this lies the positive addi- 

 tion which it may be possible for students of modern pathology to 

 make to human knowledge. 



Compare for a moment how favourably situated our "disease germs" 

 are for study in this connection, as opposed to higher organisms. 

 Take man — an organism made up of infinitely numerous parts, every 

 organ composed of an infinite series of living cells — consider what 

 must happen before a change even of type is possible, to say nothing 

 of a change which will permanently perpetuate itself in the offspring. 

 Why, infinite generations would be required before a iy\)Q differen- 

 tiated from the present could become permanent and perpetuate itself, 

 and infinite generations would comprise for man a number of years 

 not measurable by ordinary human calculation. 



In our "disease germs" we have on the other hand a "simple 

 organism," differentiated, perhaps, not even as highly as the indivi- 

 dual "cell" in any one human organ. Not only is this organism low 

 in the scale of life, but it has a power of multiplication which renders 

 infinite generations possible in an extremely short time. A few days 



