282 H. H. WILDER, 



greater number of separate pieces and an increased 

 irregularity in their disposition. This will be seen to» 

 be the exact opposite of the theory advanced by Gegen-^ 

 BAUR (No. 5) according to whom there arise, from a pri- 

 marily simple piece, five pairs of centers from which 

 are formed the definite cartilages. These centers are 

 called by him "trübe Stellen" and would thus represent the areas of 

 commencing degeneration rather than centers of origin 

 of the subsequently important elements. 



The phenomenon of the transformation of hyaline cartilage into 

 fibro- cartilage or a similar tissue appears to be of frequent 

 occurrence especially in the case of laryngeal cartilages. Kölliker 

 (No. 10, p. Ill) states that "Im Alter wird die Grundsubstanz 

 gewisser echter Knorpel gern faserig und in ihren chemischen Eigen- 

 thümlichkeiten derjenigen der Netzknorpel ähnlich, was, zu- 

 sammengehalten mit der Thatsache, dass an gewissen Orten, am 

 schönsten an der Spitze und am Proc. vocalis der Cartilago arytaeno- 

 idea von Säugern und Menschen Netzknorpel und echte Knorpel un- 

 mittelbar in einander übergehen, beweist, dass diese zwei Knorpelarten 

 nicht scharf von einander zu unterscheiden sind". 



Gegenbaur, also, has noticed that in the case of the epiglottis, 

 the primitive hyaline condition is modified to the form of elastic car- 

 tilage. "Der Knorpel der Epiglottis ist somit phylogenetisch aus einem 

 hyaUnen Zustande hervorgegangen und hat erst bei echten Mammalia 

 die Modification in elastischen Knorpel erworben, während er bei den 

 promammalen Monotremen den primitiven Gewebszustand auch beim 

 erwachsenden Thiere beibehält" ^). 



I am aware, that my results as stated above rest mainly on the 

 comparison of adult forms, and need the confirmation obtained only 

 through the development history. This incompleteness has been rather 

 that of necessity than of desire, as larval and embryonic forms of 

 these lower Urodeles are either unknown or unobtainable. 



All that I have been able to obtain in this line, is a set of young 



1) Since finishing the present article , Prof. Wiedbksheim has 

 called my attention to a paper by Si'URGAT, a pupil of his. The paper, 

 which is at present in press treats of the external cartilages of the 

 human nose, and explains their formation by exactly the same proce- 

 dure that I have given in the case of the Amphibian laryngeal car- 

 tilages, i. e. a mechanical separation into more or less constant elements 

 by the strain exerted by the growth of surrounding parts. 



