NOTCHES AND FISSURES OF THE SPLEEN. 423 



border. In two cases out of the 113 the fissures did not reach 

 either border (see fig. 2). 



Although, as a rule, only one fissure is present, an inspection 

 of the tables will show that two are by no means infrequent. 



Notches on the inferior border are not very common, still 

 they occurred in 9 out of the 113 spleens (8 ^), (see col. 7). 



With regard to the meaning of these notches and fissures, I 

 at one time looked upon them as remnants of a primitive 

 lobulation of the spleen, such as one finds so often in the 

 kidneys, liver and lungs of lower animals, but more lately I 

 have regarded them as secondary developments caused by a 

 crumpling of the viscus through pressure, and by its growth 

 being checked by traction at certain points. It may perhaps be 

 worth while seeing what comparative anatomy and embryology 

 have to tell us on these points. 



Tracing the morphology of the spleen backward from man, 

 we find that in the Anthropoids it is less notched, but among 

 the lower monkeys and lemurs notches are common enough. 



Fig. 4.— Spleen of Green Monkey, showing hilum. 



Fig. 4 shows the spleen of a green monkey (Cercopithecus 

 callitrichus) with three notches. The Carnivora are remarkable 

 for the frequence of notches on all the borders. I have found 

 them in the following representative series: cat, lion, civet, 

 suricate, kinkajou, coati, dog, wild dog (Otocyon), fox, polecat, 

 otter, ordinary seal and crested seal. Fig. 5 shows an extremely 

 notched spleen from the ordinary seal (Phoca vitulina), though 

 in other animals of the same species there were not nearly so 

 many notches. 



The Ungulata contrast very sharply with the Carnivora ; I 



