260 



the Mollusca!! hypodermis is claimed by Prof. Lankester to be con- 

 trary to my statements in reference to the Arthropod eye. It is asto- 

 nishing that one who deplores the inability of other people to observe 

 correctly the contents of books, should show such an imperfect know- 

 ledge of the paper he is criticising as Prof. Lankester does in this 

 last remark. There is nothing whatever contradictory in my description 

 of the nerve endings in Molluscs and Arthropods. In fact, the inner- 

 vation of the Molluscan hypodermis, according to my description, is 

 exactly the same as that in the Arthropod ommateum, a fact 

 which I have explainedin the text and illustrated by more 

 than twenty diagrammatic drawings! Had Prof. Lankester 

 understood the composition of the retinophorae, he would not have 

 regarded the presence of an axial nerve in the crystalline cone cells 

 as in any way contradictory to what I have described in Molluscs. 



10) Prof. Lankester, in criticising my ))treatment« of Gre- 

 nadier, states: «On p. 728, this young American, after citing an 

 opinion published by Prof. Gre nach er, says: ,This he knows is ab- 

 surd and cannot be true.'« The facts are these: Prof. Grenacher, in 

 order to illustrate an opinion, compared a row of retinal cells to a line 

 of soldiers. In my opinion this comparison led to an absurdity, i. e. to 

 the supposition that each retinal cell had a rod, a pigmented and a 

 colorless portion. This, I said, »he knows is absurd and cannot be 

 true,« because, as everyone will admit, it is contrary to fact; some 

 cells bear rods and some do not, some are deeply pigmented and others 

 colorless. One, however, is led to infer from Prof. Lankester's criti- 

 cism, that I said in so many words, that Prof. Grenacher knew his 

 own opinion was absurd and could not be true, whereas my state- 

 ment referred, not to Prof. Grenacher's opinion, but simply to an 

 inference which I myself drew from his comparison. 



11) Prof. Lankester declares that it is Dr. Patten's avowed 

 intention to follow his own course, picking out such facts as suit his 

 theories, and denying the existence of those which do not.« Prof. 

 Lankester goes even farther and asserts that Dr. Patten »openly 

 professes that he has made it his habit in constructing his 

 views upon the structure of eyes« to pick out those facts which 

 «support a favorite theory, or amplify a startling generalization, and 

 ignoring or flatly denying, without troubling to bring them to the 

 only test recognized by loyal students of nature, those which cannot 

 be thus used!« 



I did say, in reference to a single case in which the 

 observations of two authors were diametrically opposed: 

 »Since the doctors disagree, it is necessary for us to choose our own 



