584 THE POPULAR SCIENCE MONTHLY. 



As far back as 1850, Colin wrote, apparently without any knowl- 

 edge of what Payen had said before him : 



The protoplasm of the botanist, and the contractile substance and sarcodo 

 of the zoologist must be, if not identical, yet in a high degree analogous sub- 

 stances. Hence, from this point of view, the difference between animals and 

 plants consists in this, that, in the latter, the contractile substance, as a primor- 

 dial utricle, is enclosed within an inert cellulose membrane, which permits it 

 only to exhibit an internal motion, expressed by the phenomena of rotation and 

 circulation, while in the former it is not so enclosed. The protoplasm in the 

 form of the primordial utricle is, as it were, the animal element in the plant, but 

 which is imprisoned and only becomes free in the animal ; or, to strip off the 

 metaphor which obscures the simple thought, the energy of organic vitality 

 which is manifested in movement is especially exhibited by a nitrogenous con- 

 tractile substance, which in plants is limited and fettered by an inert membrane, 

 in animals not so. 1 



In 1868, thinking that an untechnical statement of the views cur- 

 rent among the leaders of biological science might be interesting to 

 the general public, I gave a lecture embodying them in Edinburgh. 

 Those who have not made the mistake of attempting to approach bi- 

 ology, either by the high a priori road of mere philosophical specula- 

 tion, or by the mere low a posteriori lane offered by the tube of a mi- 

 croscope, but have taken the trouble to become acquainted with well- 

 ascertained facts, and with their history, will not need to be told that 

 in what I had to say " as regards protoplasm," in my lecture " On the 

 Physical Basis of Life," there was nothing new ; and, as I hope, noth- 

 ing that the present state of knowledge does not justify us in believing 

 to be true. Under these circumstances, my surprise may be imagined, 

 when I found that the mere statement of facts, and of views, long 

 familiar to me as part of the common scientific property of Continental 

 workers, raised a sort of storm in this country, not only by exciting the 

 wrath of unscientific persons whose pet prejudices they seemed to touch, 

 but by giving rise to quite superfluous explosions on the part of some 

 who should have been better informed. 



Dr. Stirling, for example, made my essay the subject of a special 

 critical lecture, 2 which I have read with much interest, though, I con- 

 fess, the meaning of much of it remains as dark to me as does the 

 " Secret of Hegel " after Dr. Stirling's elaborate revelation of it. Dr. 

 Stirling's method of dealing with the subject is peculiar. "Proto- 

 plasm " is a question of history, so far as it is a name ; of fact, so far as 

 it is a thing. Dr. Stirling has not taken the trouble to refer to the 

 original authorities for his history, which is consequently a travesty ; 

 and still less has he concerned himself with looking at the facts, but 

 contents himself with taking them also at second-hand. A most 

 amusing example of this fashion of dealing with scientific statementa 

 is furnished by Dr. Stirling's remarks upon my account of the proto- 



1 Cohn, " Ueber Protococcus pluvialis," in the "Nova Acta " for 1850. 



2 Subsequently published under the title of " As regards Protoplasm." 



