748 EXPERIMENT STATION RECORD. 



Bordeaux mixture, but. one application of that fungicide made as soon as the 

 fruit baH set apparently bad no effect. A bibliograpliy of the fungus is given. 



The appressoria of anthracnoses, H. Hasseldring {Bot. Gas., -'i2 {1906), 'No. 

 2, pp. 13.j-l'ii. fi!/s. 7). — A number of observers have reported the preseuce of 

 peculiar sporelike organs which are produced by the germ tubes of spores of 

 various anthracnoses. By some these are regarded as secondary spores, but it 

 ;;ppears that Frank was the first to recognize their true nature, and he gave 

 to the organs of this class the name appressoria, or adhesion organs. 



In order to clear up some of the uncertainty regarding these organs the 

 author carried on experiments and observations on the appressoria of the 

 apple bitter rot (Glarosporimn fructigenum). His experiments show that the 

 formation of appressoria is induced by a contact stimulus, and in the presence 

 of abundant nutrient material the germ tubes lose their power to react to con- 

 tact stimuli, and the formation of appressoria is inhibited. 



The appressoria were found to germinate readily on a slide when covered 

 with nutrient solution, and the process of penetration was studied by sowing 

 spores on berries of Berber is thniibergii. From the poi'e on the lower flattened 

 side of the adhesion disc a slender tube was observed to protrude, which dis- 

 solved a narx'ow channel in the wax covering of the cuticle. Although at first 

 very slender, the hypha soon became larger and dissolved large cavities in the 

 wax. Finally the cell wall was perforated and the mycelium branched freely 

 within the cells. The penetration of the germ tube through the cuticle of the 

 apple has been frequently observed, but contrary to former supposition no i)re- 

 vious injury or puncture of the fruit is necessary. 



The behavior of the appressoria of the bitter rot fungus under natural con- 

 ditions is biologically interesting. The spores of this fungus are embedded 

 in a gelatinous substance, which causes them to stick together in waxy masses 

 when dry. By reason of this condition the spores can not be distributed by 

 the wind, but are almost entirely dependent on rain for dissemination. This 

 has been shown in the conelike distribution areas observed on apple trees due 

 to the washing of the spores from the limb cankers to the apples below. 



Since rain is the chief factor in distributing the bitter rot spores, the effect 

 of wetting and drying on the vitality of the spores and the appressoria was 

 studied. It was found that the appressoria are much more resistant to the 

 injurious effect of drying than the spores. 



In conclusion the author states that the sporelike organs formed by germ tubes 

 ol the anthracnoses are adhesion organs, by means of which the fungus is at- 

 tached to the surface of its host during the early stages of infection. They are 

 not suited for dissemination and are therefore not to be regarded as spores. 

 The adhesion discs ai'e formed as a result of stimuli from mechanical contact 

 acting on the germ tubes, and under natural conditions the appressoria are 

 formed as soon as the germ tube emerges from the spore. 



A disease of the Carolina poplar, G. Delacroix (BuI. Trimest. 8oc. Mycol. 

 France, 22 {1906), No. 4, PP- 239-252, pi. 1). — A description is given of a disease 

 of poplars due to Dothichiza populea, a previous account of which has been 

 noted (E. S. R., 18, p. .551). 



" Cluster-cup " disease of conifers, G. Massee {Roy. Bot. Garil. Keir. Bui. 

 Misc. Inform.. 1907. No. 1. pp. 1-3. pi. 1). — A description is given of the cluster- 

 cup on certain species of conifers, the fungus being Cali/ptospora (jorppcrtiana. 

 In the alternation of generations, the fungus occurs also on Vaccinium, but it 

 has been found that where conifers are not present the fungus can reproduce 

 itself entirely on its Vaccinium host. 



The cluster-cup stage is reported as occurring on various species of fir, in all 

 10 species having been observed as host plants, while the resting spore condition 



