248 Black Currant Eehvorm 



the black currant bud should present no difficulty in the matter of 

 invasion is not surprising, seeing that this parasite measures at its 

 greatest breadth, one half that of the acarid whose facility for entering 

 the buds is notorious. 



The worms are gregarious in their habits and enter the buds in 

 colonies composed of individuals varying in number from a few dozen 

 to many hundreds. When within the buds their number increases 

 by reproduction, and conceivably by the arrival of additional migrants. 



Reproduction continues throughout the year. There appears however 

 to be a preponderance of females over males in the spring of the year, 

 and eggs and larvae are extremely abundant during that period. 



Experiments undertaken with the desire to discover details of the 

 larval life of the worm, gave in all instances negative results. It was 

 found that to keep the young worms on dissected bud leaves for any 

 length of time in a sufficiently moist atmosphere, was an impossibility, 

 as the worms invariably fell a prey to bacteria and the host to fungoid 

 diseases. The method of infecting sterile host plants with eggs was 

 also tried, but the delicate bodies were either damaged by the trans- 

 ference, or from other causes failed to develop in requisite numbers for 

 the accurate description of the successive larval stages. Several 

 artificial media were tried, but the worms failed to develop in them. 

 The experiment had therefore to be abandoned as impracticable. 



The habits of the worms within the bud are lethargic, their move- 

 ments being so slight that the dissection of an attacked bud causes 

 the worms which adhere to either side of the separated leaves to shew 

 a slight recoiling movement only. They may thus, when a low powered 

 dissecting microscope is used, be readily overlooked among the hairs 

 that fringe and cover the leaves of the bud, being approximately of 

 the same length, breadth, and colour, as these structures. 



A characteristic grouping of worms takes place when the colonies 

 have become strong within the buds. Such grouping is at once inter- 

 esting and enlightening, in that it presages migration. 



Thus on dissecting a bud in which the worms are numerous, it is 

 seen that between the leaves, and especially at their extreme bases, 

 bodies are present which closely resemble fragments of cotton wool, 

 or the strands of some densely interwoven hyaline fungoid mycelium. 

 Such bodies, which can be seen without a lens, and lifted intact on a 

 dissecting needle, are, when examined microscopically, seen to be 

 composed of worms in the aggregate, densely interwoven, and longi- 

 tudinally extended. Many hundred worms are found in these closely 



