COMPARATIVE ANAT<>MY. 



the teat may be described as true <>r secondary (Mar- 

 su ]i:ils, Rod i 'ii is (? all), Lemurs, Monkeys, and Man), and m 

 the former as a pseudo- or primary teat (Carnivora, Pigs, 

 Horses, and Ruminants). The latter condition is already 

 sketched out in certain Marsupials rinil<ni'ji4<i n/l<iina}. 



As a rule the number of teats corresponds to the number of 

 young horn at a time. Tht-y an- often situated in two nearly 

 parallel row.s along the ventral side of the thorax and abdomen, 

 which gradually converge towards the inguinal region: in other 

 cases they may he restricted either to the inguin-d Tngulates and 

 Cetaceans) or to the thoracic region (Elephants, Sircnia, many 

 Lemurs, Cheiroptera, and Primates). 



In the human malr, the mainmary apparatus becomes aboited, though 

 usually at liirth ami puberty true milk, the sn-ralK-.l ''witches' milk" 

 (Hexenmilch), is produced. Male gnats ami castrated sheep liavc aNo been 

 known tn give milk. The occasional existence in men of supernumerary teat-, 

 ami in women of supernumerary mammse and teats (polymastism and poly- 

 thelism) is very remarkable. They arc usually situated in the thorarir region, 

 and must l>r i-]i.-idnvil as an atavism tn a charaeteristie primitive 1'nrm which 

 possessed numerous teats, and which produced a number nl' young at a time. 

 Surh a transition I'mm polymastisiu to bimastism may be seen plainly at the 

 piv-eiit day in the Lemurs : in them the inguinal and abdominal teats are under- 

 going a retmgresM\ e met.-imiirjihnsis, while a single pair of tlmraeir teals n-main 

 well develnped.' This ace. .rds with the fact that nm-t Lemurs bear only a pair 

 of youn.L' "lies at a time, which they carry with them :it the breast. 



The glands, which are at first solid, become secondarily hollowed 

 out and differentiated into acini, mammary ducts, milk 

 sinuses, and excretory ducts. The whole intermediate tissue 

 during lactation is filled with white blood-corpuscles (leucocytes), 

 and possibly the well-known structural elements of milk, known as 

 colostrums and milk-spheres, owe their origin to these corpuscles, 

 which have passed through the walls of the acini. 



BIBLIOGRAPHY. 



< ' \l:l:lf i:K, .T. !>! ;.../. m/ifi.rm"/- l:'n/ ;,/.; li/,i<i ,/>, A///"'' 'I'mix 

 foi Ai'i-liirf. i/ii'/.-ru.i. .I/nit. 1'xl. .\.\I\'. l* s l. 



l)Mi:i:"i\\ SK i. I;, vox. > ; ,r, ;/,, // . i ;, liiini' . A""//'/-//-/>x. Studie, Wicii, 18S.". (With 



in I.I.H. 

 I-VKI.I , A.. HIM! \\'i nu i;-n M M, \\.~--lii' .liiii/i>iiii'<- i/.-.v /'/K.SV//.-.S-. ]'.r;iuns,-li\vi'i", 



186482. 

 QROBNBAUB, C. --/"/ .v<>i-/iiit. ii-* -V./././v. .i/< -/-/'/I. ./"/(//-(/.//, i;.i. x. 1885. '/m- 



-/..,, Kenntnw der Ziteen der S&ugelhiere. Mnr/i/n.l. ,11>rl>. M. I. 1876. 

 IFfXi.i:v, T. II. '/' >juni' nt'irii iii-iin iix. Toild's i.'iii-ln/i n/.'-i nt' AiKi/. Hint 1'liiixinl. 

 l\ i 1:1:1 i: i . I '. U'l"i- ili'- ll'int der H'/ttiU'ii Hii'! niuli-,1- //"//////,/.,,, .//,//. 7'. 



///./. r. .IIHI/II in,'--, l!i|. Mil. 

 Ki \\i-' II, II. /.in- .\/<ii-j>/iii/ii</i' <! i- Xi'iii'i ii . Mni-jiliiil. Julirl'. 1'nl. IX. 



L88 



l.i n ii ri N-I i : late, .\i-i-li.f. /..////.-/. .1,1, if. is;>. 



Li'.vi'i'.. I ' ber '// <///V///. /.'../../.(';/;/// ./'/ .linj,/ii/ii-ii. .lr<-/i. f. //////. 



Anatomie, li.l. Ml. 1876. 

 l,i-i,. I. Uebtr Wandenellen in l-'.fitlnl. Archw f. ,/////>. .l,i,it. 1!<1. XV. 1885, 



mnl '/.""I. Anzeiger, \. i:^, \'II. 



1 III HilfHll. mil I' (/,-/.>. /\ till- sj|i U 'l.- ]i:ij| nf teatfl 1- Mlll.lt. ,1 nil till' MIlll 



