138 BIOLOGICAL LECTURES. 



it were, there is no likelihood of confusion with it or with 

 Camper's cJiiasma tendiniini. The chiasma is and always will 

 be that of the optic nerves. The use of any qualifier suggests 

 undesirable variations, like chiasma nervorwn opticorimi and 

 commissura optica. Furthermore, the sufficiency of the unin- 

 cumbered mononym is practically conceded by the German 

 committee in designating one of the subarachnoid spaces as 

 cisterna chiasmatis ; see also His ('95), 171, line 8.^ 



Thalamus. — This term may naturally be mentioned here. 

 In the German list the adjective opticus is omitted, and His 

 makes the following remark ('95, 7, lines 1-3): " Wir stimmen 

 unsererseits vollig bei, wenn das Wort Thalamus kurzweg an die 

 Stelle von Thalamus opticus gesetzt wird." But it is worthy 

 of note that thalamus is strictly an idionym, and that the only 

 valid excuse for the addition of the adjective is a desire to aid 

 the student's memory by the association with the optic nerve. 

 As a matter of fact, no case of real advantage is known to me, 

 and the frequent repetition of the adjective may easily become 

 a burden, as pointed out by me in 1888. 



Callosum vs. corpus callosum. — Corpus callosum is the most 

 familiar type of a large group of anatomic names. In 1889, 

 including unusual synonyms, I recorded one hundred neural 

 polyonyms of which corpus constituted the initial word. Ten 

 such remain upon the German list (viz., corpus restiforme, cp. 

 trapezoideum, cp. medullare, cp. quadrigeminum, cp. mamillare, 

 cp. geniculatum mediate, cp. gnc. laterals, cp. pineale, cp. callo- 

 sum, cp. striatum), and their genitives are correspondingly in 

 evidence. 



It must be admitted that corpus callosum is rather attractively 

 sonorous. It is easily pronounced, and even, like qiLadrupedante, 

 "runs trippingly from the tongue." ^ But that is no reason 

 for the retention of a word which is not merely needless, but 

 really burdensome by reason of the frequency with which 

 certain parts are mentioned. In one short paper {Brain, 

 October, 1885, 377-379) coipus callosum occurs twenty times, 



1 The word chiasma is discussed at some length by Hyrtl ('80). 



2 A similar concession has been made {Science, June 22, 1S88, editorial) to the 

 claims of proper names X-iSa^ Johnny McWhorter, which are euphonious and easily 

 remembered. 



