DISEASES OF PLANTS. 1055 



stem at or just below the surface of the soil. The cortex separates 

 readily from the wood, the pith is attacked quite easily, becoming- 

 water-soaked in appearance and filled with hyplne. 



Penicillium as a -wood-destroying fungus, II. M. Waiid {Ann. 

 Bot., 12 (1898), No. 48, pp. 565, 566). — Spores from pure cultures of 

 Penicillium were sown on sterilized blocks of spruce wood cut in March, 

 and were found to grow freely and develop large crops of spores. Sec- 

 tions of the infected wood show that thehypha- of the mold entered the 

 starch bearing cells of the medullary rays, consuming the whole of 

 the starch. In cultures 3 months old the hyplne were seen deep in the 

 wood, passing from tracheid to tracheid through the bordered pits. 

 Control sections, kept side by side with the others but not artificially 

 inoculated, showed no trace of the mold. On account of the common 

 ccurrence of this fungus and its well known resistance to fungicides 

 it must be considered an important destroyer of timber. 



Nematode worms, G. E. Stone and 11. E. Smith (Massachusetts 

 Hatch ISta. Bui. 55, pp. 67, pis. 1:2, jigs. 2). — After describing the symp- 

 toms of nematode injuries, comparisons between the galls caused by 

 nematodes and those of club roots, leguminous tubercles, insects, etc., 

 the authors give in considerable detail descriptions of the parasitic 

 gall-forming nematode, Heterodera radicicola. The life history of the 

 different forms of this nematode are described, from which it appears 

 that the young worms come into the soil from previously infected plants 

 and wander about until they find roots suitable to their attacks. Forc- 

 ing their way into the younger portion of the roots they embed them- 

 selves in its tissues, and this irritation causes an abnormal develop- 

 ment of the root. The worms increase in length and much more in 

 diameter, assuming a spindle and afterwards a (dub shape. The females 

 continue this swelling process until they have the shape of a gourd 

 and are of a size just about visible to the naked eye. By this time 

 they are mature and after being fertilized produce eggs. The life 

 period of the female is said to be about weeks. The male worms do 

 not remain in the swollen form but after about 4 weeks from the period 

 of entering the root they change into a slender worm like form which 

 enables them to move about and seek the females with which they 

 copulate, and then perish. While the worms are developing the abnor- 

 mal growth of the root continues and results in the gall-like swelling 

 or enlargement and such a disarrangement of the tissues that the 

 progress of the sap through the plant is hindered. 



An historical review is given of some of the earlier literature relative 

 to this pest and the identity of the species is discussed. The authors 

 think that H. radicicola and H. schachtii are probably one and the 

 same species. 



The second part of the bulletin treats of the economic consideration 

 of the subject relative to means for controlling these pests. In north- 

 ern United States the greatest amount of injury done is to plants in 



