416 SUMMARY OF CURRENT RESEARCHES RELATING TO 



under " zone-invasion.'" Each species of marine plant is normal to 

 only one zone, and if the species invades any other zone it is because it 

 finds there the proper temperature conditions for its continuous exist- 

 ence. The proper temperature seems certainly to be that which is most 

 intimately connected with reproduction. Thus species of warmer zones 

 may esist spotwise in a warm spot or area in the midsL of cooler waters, 

 or vice versa : the extent of such invasions depending naturally upon 

 the intensity and duration of the unusual temperature. Details are 

 given of the respective ranges of the five species of marine algae men- 

 tioned above, and also of Zosfera marina, as instances of zone-invasion. 

 In conclusion, the author states that stenothermy is the rule both from 

 the point of view of distribution and of physiology, at least so far as 

 effective reproduction is concerned : eurythermy is largely, if not 

 entirely, a matter of endurance of a wide range of temperature, much 

 of which endurance is due to the power to enter into a condition of 

 rigor after certain extremes of temperature of either direction are passed. 

 A study of the various reasons for zone-invasion assists greatly in making 

 these facts apparent. E. S. G. 



Fung-i. 



Ocellus Function of the Subsporangial Swelling' of Pilobolus. — 

 A. H. R. BuLLER {Trans. Brit. My col. Soc, 1921, 7, 61-4). The 

 writer describes the mechanism of spore discharge in Pilobolus. Under 

 the influence of light — i.e. the sun striking on the swelling below the 

 sporangium — the stipe immediately below reacts by growing in length 

 most rapidly on the side nearest the spot of light, and thus bending as 

 a whole : the swollen portion moves about its base, till finally the 

 sporangium is directed towards the source of brightest light. Discharge 

 is secured by the rupturing of the wall below the sporangium, and the 

 cell-sap is squirted out at the top, carrying with it the sporangium to a 

 considerable distance towards the open — on to grass, etc., where cattle 

 feed. A. Lorrain Smith. 



Isoachlya, a New Genus of the Saprolegniaceae. — C. H. Kauff- 

 MAN {Amer. Joarn. Bot., 19iU, 8, 231-7, 2 pis.). The genus is 

 characterized and distinguished in the main by the presence of the 

 cymose (or Achlya) mode of formation of secondary sporangia, coupled 

 with diplanetic zoospores. The author lists three species that exhibit 

 thef.e characters : — (1) Isoachlya toraloides Kauffm. & Coker sp. n. : 

 (2) 7. parndoxa (Coker) comb. nov. : and (3) /. monilifera (De Bary) 

 comb. nov. The new species was collected in a shallow pool over peat- 

 like organic remains and cultivated on the house-fly. Full details of 

 the cultures are ffiven. A. L. S. 



Cordyceps in New Zealand. — G. H. Cunningham {Trans. New 

 Zealand Inst., 1921, 53, 372-82, 4 pis., 8 figs.). The author gives a 

 historical sketch of the genus, species of which are popularly known as 

 vegetable caterpillars, vegetable wasps, etc., the old idea being that the 

 genus represented the transformation of insects into plants. The dis- 

 tribution of Cordyceps is world-wide : not much is known of the life- 



