December 6, 1901.] 



SCIENCE. 



899 



and shaking these roots up in melted agar and 

 plating there develops, at 37° C, in the course 

 of a few days, from one to five circular colonies 

 of a fungus which grows rapidly and assumes a 

 salmon-pink color. Cover-glass preparations 

 made from these colonies contain numerous 

 sickle-shaped segmented spores, characteristic 

 of Fusarium. 



There are, according to Dr. Erwin F. Smith, 

 about twenty-five known varieties of this fungus. 

 Some are strict saprophytes, others are para- 

 sitic on grains and plants, and others are patho- 

 genic to plants. No Fusarium has, however, 

 been known to be pathogenic to animals. I 

 would, therefore, pending the present investiga- 

 tion, which will require some time, propose the 

 name Fusarium equinum nov. spec. 



Victor A. Novgaard. 



Washington, D. C, 

 Nov. 14, 1901. 



EHIZOCTONIA AND THE POTATO. 



Attention has been called recently to the 

 parasitic nature of Rhizoctonia on various 

 plants in the United States by Dr. B. M. Dug- 

 gar and Professor F. C. Stewart. Observations 

 at the Colorado Experiment Station on the rela- 

 tion of this fungus to the potato have brought 

 out some interesting facts. During the spring 

 months sclerotia develop freely on tubers and 

 young sprouts in sacks and bins, A few 

 affected tubers in a sack or bin of clean tubers, 

 under favorable conditions, will spread the 

 disease and in a short time render the entire 

 lot worthless for seed. Affected tubers used 

 for seed transmit the disease to the young 

 plants, and these in turn to the following crop 

 of tubers. Under proper conditions the fungus 

 attacks all parts of the potato plant and in all 

 stages of growth, but it is most destructive to 

 the softer tissues. The weaker plants are often 

 killed before they reach the surface of the 

 ground. Those which are able to withstand its 

 earlier attacks are apt to suffer more or less 

 injury from it later in the season. 



Little potatoes are produced by the fungus 

 injuring the tuber stems in such a manner as 

 to prevent free transportation of plant food 

 between the main stem and tubers, or by com- 

 pletely cutting off" the tuber stem while the 



tubers are small. When the tuber stem receives 

 an injury sufficient to check the free transpor- 

 tation of plant food, the food accumulates 

 above the injury and soon excites the buds on 

 the tuber stem above this point into growth. 

 These buds develop into tubers. The fungus 

 may continue its work and in time kill back 

 the tuber stem, or it may cut off this stem 

 above the newly formed tubers. If the tuber 

 stem is attacked just as it grows out of the 

 main stem adventitious buds may push out on 

 the main stem around the injured point. These 

 usually develop into short-stemmed or stemless 

 tubers, forming bunches of small tubers. If 

 the roots are badly injured the food supply is 

 reduced and the plant puts out weak tuber 

 stems. These stems are easily cut off by the 

 fungus and the plant usually sets few or no 

 tubers. The food which it is able to take up 

 is used mostly in top development. The leaves 

 become thicker, have a tendency to crinkle 

 and take on a yellowish tinge. When the 

 roots are less severely injured but the free 

 transportation of food to the subterranean 

 stems is interfered with, excessive top develop- 

 ment is produced, and the axillary buds may 

 develop aerial potatoes. 



Aerial potatoes may be produced artificially : 

 (1) By ringing the stem ; (2) by tying a line 

 firmly around the growing stem ; and (3) by 

 removing the subterranean tubers as soon as 

 formed. 



Sclerotia are often found on the surface of the 

 larger tubers. Apparently these sclerotia do no 

 injury, but experiments show conclusively that 

 scabbing and browning of tubers may be pro- 

 duced by this fungus. 



The corrosive sublimate treatment is promis- 

 ing as a preventive of this disease. 



F. M. EoLFS. 



FoET Collins, Colo., Nov. 11, '01. 



THE WORK OF THE 'ALBATROSS.' 

 Students of marine zoology will welcome 

 the appearance of the brochure just issued by 

 the U. S. Fish Commission, compiled by C. H. 

 Townsend, and entitled, ' Dredging and Other 

 Records of the Steamer Albatross, with Bibli- 

 ography Relative to the Work of the Vessel.' 

 This useful paper contains in condensed form 



