MAM.ANESE OF THE LAMELLIBRANCHS. 163 



Tissue. Per Cent. Per Cent. Per Cent. 



Ash. Mn in Ash. Mn in Tissue. 



Mi; 6.0 4.87 0.293 



is part .... 14.5 5.73 0.831 



brous part 32.0 4.66 1-492 



V ins ....27.0 5.31 J-434 



<']' ---33-5 4-89 1-638 



M.I: . . .48.0 5.12 2.457 



..39.0 5.85 2.107 



I .37.0 2.024 1-749 



I 1 ' rh.ip- the most interesting result of these analyses was the 

 pp -. -in ( , ,1 ill,- 1 1. mem in the eggs and embryos, showing clearly 

 that manganese is not an adventitious element picked up by 

 tin- ,i<ltili .UK! ln-lil in the tissues from inability to excrete it 

 ..nnple. iron compounds may be in the mammuli.m 



. !! after -'Main diseases involving great destruction of red 

 les. 



Another inl ng |>oint brought out in the above table 



i- i In- i mineral content of such a tissue as tin 



in. inilr. h- a-h content, of 48.0 per cent, puts it in a class with 



m. mini. ili. mi is tissue, though unlike the latter the mantle 



li .ui'l pliable. This is a type of tissue resembling no verte- 



n <>r tissue of which we are aware. It seems probal-1 

 that it- I inn ti.in as a gland secreting the shell must have some 

 n \\ith the high mineral content. 



II ivii !>li-hed as we In-lieve the normality of the element 



ni.m^.iiH-M- in the tissues of the I'nionida?, the question as to 

 it- . infill naturally presents itself. It is hardly to be supposed 

 th.it .m .iniin.il of so great complexity as a lamellibranch would 

 trate the element from its highly dilute solu- 

 tion-, in lake- .md streams. Such concentration is usually ]> r- 

 tdiiiu-il l>\ lc.\\rr forms of lift- which are then obtained as fo<><l. 

 In tin the Tnioniche the food origin of manganese i- 



nnu h iii"iv .-It-.irly apparent than is the food origin of copper 

 in m. m\ !' the h.emocyanin-bearing animals. The water- in 

 \\ hi. h t he mn els are found have invariably contained the I >n >\\ n 

 m. i e- .M the manganiferous crenothrix mixed \\iili di.ii.m-, 

 .md ether pl.mrton forms which very probably contain m.m-.i- 

 IUM- .il-o. And this brown slime seems to be the normal l"o<,d 

 M! these mn el- so far as our observations exti-nd. In Ontario 



