256 



that the specific cellular peculiarities obtain throughout the entire 

 shoot system, and need only the stimulus of definite environ- 

 mental conditions, either external or internal, to make them 

 operative. 



In this connection it would be desirable to know whether the 

 presence, in any portion of the potato stem, of a superabundance 

 of food materials would operate as a stimulus, causing the exces- 

 sive formation of parenchymatous xylem cells, which, gorged 

 with the reserve food, make up the greater part of the bulk of 

 the tubers. It is well known, through the researches of Knight 

 and others, that, if the flow of food materials is diverted from 

 incipient underground tubers by removing them as fast as they 

 begin to form, this material will accumulate in portions of the 

 aerial stem, causing tubers there. In the specimen in question, 

 translocation of digested food became established toward and into 

 the developing "sprouts," but elongation of the latter was not 

 favored because of the very slight water supply from without. 

 It does not seem improbable that a combination of these two 

 conditions alone would be sufficient to produce the tuber, even 

 in daylight. 



"Two new coralline Algae from Culebra, Porto Rico," by Dr. 

 Marshall A. Howe. 



Dr. Howe exhibited and discussed briefly specimens represent- 

 ing two rather large and conspicuous kinds of non-articulated 

 corallines which were secured during a visit made last March to 

 the island of Culebra. These have been studied in collaboration 

 with Dr. M. Foslie, of Trondhjem, Norway, and a joint paper, in 

 which the two new species are to be described and illustrated, is 

 soon to be published. One of the species is a Goniolithon which 

 seems to have its closest affinity among the forms already de- 

 scribed in a species originally found on the island of Funafuti, 

 of the Ellice Islands group, in the South Pacific. The second 

 species, a LitliopJiyllum which forms columnar flat-topped masses 

 sometimes a foot in height, is evidently a reef-builder at Culebra, 

 and like the other, curiously enough, finds its nearest relative in 

 a species originally described from Funafuti and since reported 

 from the Maldives in the Indian Ocean. The speaker remarked 



