NOTES AND ABSTRACTS. 



875 



They first swell a little and become thick in proportion to their length, 

 then at one end a germ- tube is pushed out, and later on another at the 

 opposite end. 



Macroconidia.— This is the kind of spore by which the form genus 

 Fusarium is commonly distinguished. They vary much in form and 

 shape according to the culture media used. In one case, which may be 

 considered typical, they were from 10 to 36 /< long and from 2 J to 6 ji in 

 diameter, 28 x ±\ f* being the most usual size. In this case they were 

 from one to five septate, usually three, slightly constricted, not sharp 

 pointed, varying from straight to very much curved, thin walled, and with 

 a nucleus in each cell. When first formed they are usually smaller and 

 less pointed than when mature, and generally without septa. The 

 formation is somewhat similar to that of the micrcconidia. In this case 

 also the time of germination varies much with the different culture media. 

 In distilled water the germination began in three hours, and in seven 

 hours practically all were germinating. The end cells usually germinate 

 first ; sometimes every cell in the spore germinates, but often one or two 

 near the middle fail to do so. 



Chlamydospores are produced as swellings of the mycelium either on 

 long, comparatively straight hyphae, or on short lateral branches. Some- 

 times there are several on the same hypha, close together like a string of 

 beads. The walls are relatively thick when mature, and seem to be made 

 up of two layers. They are smooth and light brown in colour. The size 

 varies from 5^ to 13 /x, about 10 /u being the usual size. All are one- 

 celled, and contain at one time a single nucleus. They seem to be more 

 resistent to unfavourable conditions than the two other kinds of spores, 

 but are scarcely to be regarded as resting-spores, since they will germinate 

 in cultures a month old in a very short time. 



On some media small masses of green sclerotia are produced, not more 

 than 5 mm. in diameter. Their true significance has not been deter- 

 mined. 



Some attention has been given in this bulletin to the species of fungus 

 concerned, and the conclusion arrived at that it should be called Fusarium 

 oxysporum (Schl.), but that it is identical with the Fusarium solani of 

 many authors ; and here no fewer than ten species, or names, are given which 

 should be accepted as more or less synonymous, and it is strongly hinted 

 that the fungus of the sleeping disease of Tomatos, Fusarium lycopersici 

 (Sacc), is probably in reality the same fungus under a different name. 

 These questions of identity will have to be settled hereafter. 



As to remedial measures, little hope is entertained of spraying with 

 Bordeaux mixture or other fungicides. Adding chemicals to the soil as 

 fertilisers has not hitherto been attended with success. Planting on soil 

 free from disease, with sound tubers, obtained from localities where the 

 disease does not occur, is certainly to be recommended. When Potatos 

 are harvested the extent of the disease is usually comparatively slight. It 

 is while they are in storage that the greater amount of destruction and 

 consequent loss takes place. Hence it is urged : — 



Plant only sound tubers on uninfected land. 



Reject badly diseased tubers, and store slightly diseased ones in a cool 

 dry place (35°-40° F.). 



