782 On the Origin of the Tae [ November, 
tested by its grittiness, which is due to inorganic crystals, and 
rhubarb should contain a high per cent. of inorganic matter. 
ther uses might be enumerated and given in this list, and per- 
haps some of them are of more importance than those mentioned, 
but sufficient has been said to show that they are probably of 
some practical value to man. It is hoped that this article will 
induce other investigators to take up this subject and find, if pos- 
sible, their exact use in the economy of the plant. 
The time is probably not far distant when we will know more 
about microscopical crystals in plants, and for that time we must 
all wait, each investigator endeavoring to do his best. 
BIBLIOGRAPHY. 
Quar. Journ. of Micros., I old ser., 20; III new ser., 243; IV new ser., 207, 208, 
09, 234, 208; V new ser., 49, 83, 140, 220, 279; VI old ser. 120; IX new set., 
232; XIII new Ser., 290, 216, 324,294, 439; XIV new ser., 108, 211; XII new 
ser., 288. 
hens ad Mag. of Nat. Hist., XI 3d ser., 13; XII 3d ser., 226, 446, 288, 365 ; XIII 
3d ser., 41, I19, 212, ae a soe XIV 3d ser., 53, 250; XV 3d ser., 38; 211, 
80, pea XVI 3d se 
Sach’s “ Text Book of oes” 4g 
Lindley’s Introduction to Botany. 
Gray’s Structural ci Systematic Botany. 
_ Flückiger and Handbury—Pharmacographia. 
w 
Miller’s Organic Chemistry. 
:0: 
ON THE ORIGIN OF THE LACI 
BY J. M. STILLMAN. 
\URING the course of an examination of a product from Ari- 
_ zona, apparently identical with the gum-lac from India, I had 
occasion to consult various works touching on the origin of this 
interesting product. 
The statements met with were in many cases contradictory, and 
the most usual statement so directly opposed to what appears to 
me, from a careful examination of the deposit and of the evidence 
on the subject, to be the truth, that I cannot refrain from at least 
_ suggesting what seems to me to be the true state of affairs. At 
the same time I wish to state, that as far as the lac insect is con- 
ses : cerned, I have not been able to find sufficient data regarding its 
anatomy and life-history to enable me to touch upon some very — 
__ interesting points in connection with the subject. Nor am I cer- 
- 1his paper was read before the California Academy of Sciences, April 19, 1880. 
