702 SUMMARY OF CURRENT RESEARCHES RELATING TO 



vital conditions — temperature, oxygen, &c. — are narrower for propaga- 

 tion than for growth. Growth may therefore continue when propaga- 

 tion is checked by the too strong or too weak action of one of the 

 conditions. (4) Growth appears to be a preliminary stage for the 

 inception of propagation. 



Propagation, therefore, whether sexual or non-sexual, exhibits a 

 physiological opposition to growth. It is a reaction of the organism 

 against conditions of the environment which are unfavourable to growth. 

 The products of sexual reproduction are better adapted for a long period 

 of rest and for the production of a vigorous offspring than those which 

 result from non-sexual propagation. 



A very copious bibliography is appended. 



Capacity of Fungi to absorb Humin-substances.* — Limiting the 

 term humus to those substances which are compounds of humin, Herr 

 F. Eeinitzer confirms in the main Hoppe-Seyler's statement as to their 

 extreme power of withstanding decomposition under ordinary conditions. 

 This however applies only to the power of living organisms to extract 

 carbon from humus. If another source of carbon, e.g. sugar, is present, 

 Penicillium has then the power of obtaining its nitrogenous constituents 

 from humus, which must therefore be regarded as a source of nitrogen 

 for soil-organisms ; whether also for mycorhiza remains to be deter- 

 mined. 



Monoblepharidese.t — Prof. G. v. Lagerheim publishes a monograph 

 of this small family of fungi, consisting of the two genera Monoblepharis 

 and Diblepharis g. n., made up of the two species D. insignis and fasci- 

 culate/,, with the following diagnosis : — Thallus simplex v. ramosus, 

 protoplasmate favoso ; zoosporangia zoosporis compluribus, biciliatis, 

 post evacuationem globulum olei continentes ; antheridia spermatozoidiis 

 uniciliatis compluribus ; oosphaerae singulae, ex parte contentus oogonii 

 ortse, periplasmate nullo ; oosporae in oogonio inclusae maturescentes. 

 Of Monoblepharis three new species are described, M. brachyandra, 

 regignens, and ovigera. 



The cell-membrane appears to consist of a pectinaceous substance 

 and chitin, with but little cellulose. The cells are multinucleate. The 

 formation of zoospores takes place without any previous division of the 

 nucleus. As soon as the antherids are formed they contain as many 

 nuclei as there are subsequently antherozoids. The oogone contains 

 only a single nucleus. After impregnation the nuclei do not coalesce 

 immediately, but remain for a time lying side by side ; complete coales- 

 cence takes place only after the warts make their appearance on the 

 wall of the oospore. Gemmae were observed on M. brachyandra. 



The Monoblepharideae are probably most nearly related to the Sapro- 

 legniacese ; they also display resemblances to the GCdogoniaceae and 

 Coleochaetaceae among Algae. 



Fertilisation of Albugo Candida.^ — The following results have been 

 obtained by Prof. B. M. Davis. 



Communication between the oogone and the antherid is established 



* Bot. Ztg., lviii. (1900) l te Abt., pp. 59-73. 



t Bih. k. Svensk. Vetensk.-Akad. Handl., xxv. (1899) 42 pp., 2 pis., and 2 figs. 



% Bot. Gazette xxix. (1900) pp. 297-311 (1 pi.). Of. this Journal, ante, p. 92. 



