582 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Collembola and Thysanura of Forth Area.* — William Evans con- 

 tinues the list published by G. II. Carpenter and himself in is 1 .)'.). In- 

 cluding Tsotoma minuta Tullberg, /. bidmticulata Tullberg, Achorvtes 

 manubrialis Tullberg, and a species of Tetracanthella - a genus not 



hitherto recorded from the British Isles — there are now sixty-six species 

 of Collembola known from the Forth area. 



Excretion in Thysanura. f — L. Bruntz finds that excretion is effected 

 by nephrocytes and phagocytes. In Machilis the nephrocytes are like 

 the adipose cells, and lie along the sides of the lobes of connective-tissue 

 in the region of the pericardial sinus. In Lepisma the nephrocytes are 

 very different from the adipose cells, but they occur again in the region 

 of the pericardial sinus, or suspended on the fibres which connect the 

 heart to the dorsal wall. 



Phagocytosis is effected by the blood-cells, and, in some cases, by a 

 phagocytic organ. This special organ occurs in Lepisma saccharma and 

 (Jtmolepisma Jineata in the pericardial septum. 



Structure and Habits of Acentropus niveus.J — M. Nigmann gives 

 a full anatomical and ecological account of this interesting aquatic 

 •butterfly, which he found in great abundance in Greifswald, on the right 

 and left of the estuary of the Ryck. The caterpillar was found on 

 various species of Potamogeton and other aquatic plants. The eggs are 

 0*5 mm. in length, furrowed on the surface, yellowish-green and opaque 

 when freshly deposited, but becoming more transparent as development 

 proceeds, till they are crystal-like when the larvae emerge. They are 

 deposited in clumps or packets on the food-plant, to which they are 

 attached by a jelly-like substance. In regard to the two kinds of eggs 

 reported by some observers, the author believes that these are fertilised 

 and unfertilised, the latter kind being transparent from the first, and 

 often deposited in an abnormal manner. The number of eggs in a 

 clump varied from 56 to 117. The period of incubation varied according 

 to temperature, usually from 14 to 21 days, but in two cases it reached 

 29 and 31 days respectively. The newly emerged caterpillar eats its 

 way into the heart of the stalk, and there passes the first few days. On 

 leaving the stalk the caterpillar makes a shelter by spinning longitudinal 

 pieces of leaf loosely together with the ends open so that it is entirely 

 surrounded by water. From this tube it stretches forth its head and 

 feeds on the leaves within reach. Four moults were observed, but it is 

 suggested that an earlier one may have taken place within the stalk. In 

 regard to the much-discussed question of larval respiration, Nigmann 

 demonstrates that the tracheal system develops very gradually, and that 

 it is only in the later larval stages that the branches reach the skin and 

 begin to be filled with air. He regards the blood as the means by which 

 oxygen is conveyed to the tissues in the earlier stages. 



For pupation a new leaf -shelter is made, this time closed at the end, 

 and the true cocoon is spun within it. The author was able to confirm 

 Muller's observation (in regard to another aquatic form) that the bubbles 



* Proc. Roy. Phys. Soc. Edinburgh, xvii. (1903) pp. 195-200 (2 figs.), 

 t Arch Zool. Exper., viii. (1908) pp 471-88 (1 pi.). 

 X Zool. Jahrb., xxvi. (1908) pp. 489-560 (2 pis.). 



