HARDWICKE'S SCIENCE-GOSSIP. 



81 



confirmatory observations by many. We have but 

 two incisors normally on each side in the premaxilla, 

 but man in reality inherits three, one of which in the 

 process of development, becomes suppressed. Which 

 one, is of very little moment, some say it is the third, 

 but the majority of observers tend to the belief that 

 it is the second or the middle one. Mr. Mattieu 

 Williams spoke of Professor Schmidt's paper in the 

 "Popular Science Monthly," on page 107 of last 

 year in his "Gossip on Current Topics," and as 

 therein is contained a succinct but full account I 

 need not descant further than this. But for a brief 

 space compare the arrangement of the tooth-territory 

 of any mammal with the same of a shark. They are 

 exactly correspondent each with each in that they 

 are both developed from the involution of epidermis, 

 which, in the foetus, bends in to form the buccal 



4. A very interesting and instructive case is this 

 one. A section through the prostate gland of a man, 

 would exhibit such an anatomy as may be seen in the 

 diagram underneath. (Fig. 36.) 



It is observed to be a structure surrounding the 

 neck of the bladder, with a pouch somewhat pear- 

 shaped running backwards and upwards in its 

 substance, yclept sinus pocularis and with a duct, the 

 common ejaculatory duct passing along through its 

 upper surface-portion. This prostate and sinus 

 pocularis is developed from that very same part of 

 the Miillerian duct which becomes the vagina and 

 cervix uteri in the female ; and moreover these parts 

 of the female reproductive organs, exactly correspond 

 to that portion of the oviduct which in the oviparous 

 vertebrates has the especial function of secreting the 

 shell. But in the recesses of the prostate gland in 



Fig. 36.— Section through the prostate gland to show the 

 sinus pocularis. 



Fig. 37. — A half-vertebra from the spine of a man. 

 After Reid. 



cavity, and called in the language of the embryologist 

 thestomodceum. In the mouth of the mammal, they 

 are localised to definite and circumscribed areas ; in 

 that of the shark, on the other hand, there seems to 

 be no law of place, and they are scattered in profusion 

 of number, hither and thither — anyhow. From 

 this Mr. Sutton concludes that man,|in his process of 

 development, has had many teeth quashed in the 

 evolution of his species, the particular lost incisor 

 being the last in order of suppression. So much so, 

 indeed, with what we would expect of atavism — teeth, 

 supernumerary teeth, sometimes assert their ancestry 

 by appearing in us, varying from a properly-covered 

 enamel organ to a conical mass of dentine. Working 

 on his lines of pathology, Mr. Sutton also entices us 

 into the opinion that some forms of odontomata, and 

 multilocular cystic growths of the jaws, are to be 

 explained as originating in the obsolete rudimentary 

 germs of such teeth as these often recurring ones. 



the adult are found small granulations of carbonate 

 of lime. And Mr. Sutton says thus, as the prostate 

 with its glandular loculi was developed from the 

 same segment of Mullet's duct as the shell-forming 

 section of the oviduct of birds and reptiles, and, as 

 in them, it was engaged in depositing carbonate of 

 lime in animal matter, so man has in his prostate a 

 witness testifying to common ancestry with the 

 feathered tribes, low down among oviparous ver- 

 tebrates. 



Supernumerary vertebra. — In Psittacus undulatus, 

 an Australian parrot, there are more vertebrae found 

 in the fcetal than in the adult condition. In the 

 Ornithoscelida, a fossil Reptilian genus, the number 

 of sacral vertebrae amounts to four or five, while in 

 the existing species the normal number is two. 

 Professor Kitchen Parker finds that the earlier stages 

 of development in the green turtle there are fifty-one 

 somatomes, but only forty-one are existent in the 



