Lyman."! 102 [March 7, 



in New York City and other localities in the east, originated in 

 Dakota. The tribe afflicted sold their bales of robes, which were 

 shipped to New York. Had the sale been prohibited and the robes 

 burnt, the disease might have been prevented. The Medical Di- 

 rector saw the importance of such a measure but was powerless, for 

 had the robes been burnt they might have charged for many silk 

 robes, bringing the half-breeds and " squawmen " to bear testimony 

 in behalf of the Indians' extortionate demands, in which the case 

 would have resulted. 



It is rather singular that there are no representatives of the Ves- 

 pertilionidce in this region. Specimens of several species occur on the 

 Yellowstone and Musselshell Rivers, but they are unknown at Grand 

 River Agency. 



Mode of Forking among Astrophytons. By Theodore 

 Lyman. 



Governor John Winthrop (Philosophical Transactions, Vol. iv,^). 

 1152, 1670) made a calculation of the number of twigs in his Stellar 

 Fish (Astrophyton Agassizii). He assumed that the increase in the 

 branches was by a uniform and equal bifurcation, so that each suc- 

 ceeding set of twigs was twice as numerous as its predecessor. By 

 this theory, a specimen each of whose arms forked twelve times 

 would have a total of 20,475 forks, or 20,480 terminal tfwigs. An 

 actual count of a specimen having twelve forks shows the terminal 

 twigs to be about 5,470, or little more than one-fourth the number 

 called for by the theory. (See Table I.) 



The question rises; what rule is observed in the forking? When a 

 shaft splits in two at its tip there result two branches, and these again 

 splitting would give four branches. But if the primitive shaft — in- 

 stead of making an equal split, continued its growth in a direct line 

 and only threw off simple twigs to the right and left, the number of 

 twigs, instead of doubling at each forking, would increase in no 

 greater ratio than the forks themselves. Thus a shaft that split 

 equally eight times would have 128 twigs; whereas a shaft with eight 

 lateral forks would present only nine terminal twigs. 



The first mode is dichotomous or forking ; and the second axial or 

 trunk-growth. 



In dichotomous growth the tip of the axis, trunk, or shaft splits in 

 two. In axial growth the trunk continues to extend, and from time 





