Vol. XLV1II March, 1925 No. 3 



BIOLOGICAL BULLETIN 



A M')D|| K ATION OF THK IRODELK TESTIS RE 

 SI LTING FROM r.KKM CKLL DEC.i \1 RATION. 



K. R. HUMPHREY. 



I-'n.in th. I i. i irtmcnt of Anatomy, School of Medicine, I'niv. r-ity ,.; 



I >e-< riptions of the I'rodele testis, particularly tho-e of the 

 icr investigators (von \Yittich. '53; Hoffmann, '7 .;. ';v 

 s l" n.rl, '76) frequently contain references to peculiarities ol 

 -inn ture, such as lobation, constriction, or reduction in -i/. 

 ( -.ni-l.il or cephalic ends. The significance of such peculiarities 

 was .ipparently hut little understood or appreciated. Although 

 makes the brief (and correct) statement that tin-.- are 

 the result of the [)rogressive and regressive changes in the 

 is, no elaboration of this view serves to show \\hether the 



\vas more than a speculation. 

 Tin- -implu -ity of the structural plan of the u--tis in many 

 I i-odi-K-s (the Plethodons, Enrycea, Desmognathus, d \rhiophil us] 

 IP. ikes the organ particularly susceptible to modi I'M .nion- in form. 

 < M" .in (!'!]-. ited, cylindrical shape (Fig. i) it is tr.i\rr-i-<l l>\ .1 

 I.Mi-ittidin.il collecting duct, more or less central in position, 

 around \\lii.li the chambers or lobules are arr.m^rd in either 

 r.idi.il or fan-like fashion, as shown in Fig. 8. The- synchronous 

 development of all the cells of the lobule, and the c.uid 

 onk-r ot development and extrusion of the germ evil-, in a 

 ot i\\\~~ t\ pe, results in normal seasonal variations that would not 

 otlirr\\i>r lie j)oible. The earlier emptying of its lobules, !<T 

 example-, retlinvs the size of the caudal portion of the testis as 

 compared \\itli that territory yet containing spermatozoa 

 (Fig. 2). Later, after the final emptying of the .interior lobules, 

 the inequality in M/e of the two regions may be quite rever-cd 

 - . 3) due to the earlier growth, in the caudal lobules, of the 

 >|u -i -matoi \ tes for the next cycle. It can be readily appreciated, 

 10 145 



