ACHLYA. 



ACHLYA. 



described at some length, that it requires no 

 special notice here. (See BLATTA.) Some 

 parts of the internal structure of the cricket 

 are very beautiful, as the tongue (PL 33. 

 fig. 23), the gizzard (PI. 34. fig. 1), and the 

 ear in the fore legs (PL 34. fig. 76). These, 

 as also the curious mechanism by which the 

 chirping noise of the male is produced, are 

 described under INSECTS. 



ACH'LYA, Nees (&?/>ro/e*7w?#,Kutzing). 

 Remarkable microscopic plants,sometimes 

 referred to the Al^se, but more properly 

 belonging to Fungi. Cienkowski has re- 

 cently confirmed the idea formerly enter- 

 tained, that Aclilya is an aquatic form of 

 the Mucorinous Fungus called SPORENDO- 

 NEMA Muscce (Empusa MUSC&, Oohn), the 

 common fly-fungus. Cohn and Al. Braun 

 deny the identity, while Berkeley thinks 

 AcJilya may be an aquatic form of Botrytis 

 Sassiana. They are found growing para- 

 sitically upon the bodies of dead flies lying 

 in water, also upon fish as salmon, salmon- 

 eggs, frogs, &c., and in some cases upon de- 

 caying plants. To the naked eye they ap- 

 pear like colourless minutely filamentous 

 tufts, adherent to such objects, forming a 

 kind of gelatinous cloud more or less en- 

 veloping them. When placed beneath the 

 microscope, the tufts are seen to consist of 

 long, colourless, tubular filaments, spreading 

 out in all directions, with or without lateral 

 branches; these erect filaments arise from 

 a kind of mycelium of ramified filaments 

 lying upon the object upon which the plant 

 grows. The erect filaments are devoid of 

 septa, narrowed upwards, and vary in thick- 

 ness, being usually of smallest diameter in 

 those cases where they are closely crowded; 

 the ordinary thickness varies from 1-1000 to 

 1-350 of an inch. The tubes contain a colour- 

 less slightly granular protoplasm, which 

 is denser on the walls ; and these sometimes 

 exhibit an irregular spiral arrangement of 

 the granules ; the granules are seen to move 

 slowly in anastomosing currents running in 

 various directions, exhibiting, that is, the 

 well-known phenomenon of the circulation 

 of cell-contents, such as is met with in the 

 hairs of Tradescantia, &c. The walls of the 

 tubes are coloured blue by iodine and sul- 

 phuric acid, therefore consist of cellulose ; 

 the contents are nitrogenous, taking a bright 

 yellowish brown with iodine ; no trace of 

 starch or chlorophyll can be detected in the 

 cell-contents in this stage, whence these 

 plants are regarded by some authors as 

 Jungi ; but, as mentioned hereafter, Prings- 



heim states that their ripe spores do con- 

 tain starch. 



Kiitzing describes a number of species of 

 this genus, tinder the name of Saprolegnia, 

 while a recent observer, Pringsheim, regards 

 them ah 1 as forms produced by varying ex- 

 ternal conditions. A. de Bary separates 

 AcJilya prolifera, Nees, from Saproleynia 

 ferax, Kiitzing, referring to the former the 

 Saprolegnia ferax of Cams and the Sapro- 

 legnia capitulifera of Alex. Braun, to the 

 latter the Aclilya prolifera of Cams, and, 

 doubtfully, the S. molluscorum of Nees and 

 Gruithuisen. The distinction between these 

 is said to lie in the details of the formation 

 and emission of the active gonidia or zoo- 

 spores; but we cannot make out satisfactory 

 differences. 



The following details respecting the for- 

 mation of the active gonidia and the resting 

 spores are given at length on account of 

 their well illustrating modifications of free- 

 cell formation. In about thirty-six hours 

 after the appearance of a specimen on any 

 body, the apices of the erect filaments 

 exhibit remarkable changes. The granular 

 protoplasm, which at first is equally dif- 

 fused throughout the tube, only densest 

 where it lies on the wall, increases in quan- 

 tity and " travels up " into the end of the 

 tube, becoming accumulated there, giving 

 it a brownish colour and at the same time 

 causing its distention, so that the upper part 

 of the tube acquires a clavate form, ronnded 

 off above. A sharp line of demarcation is 

 soon formed by the division of the primor- 

 dial utricle, followed by the production of a 

 septum, which shuts off this clavate joint as 

 the sporange ; and a little projecting pouch 

 or beak is developed at the summit, or 

 sometimes a little below this on one side. 

 The contents,becoming still more condensed, 

 again apply themselves as a thick invest- 

 ment on the wall, leaving a lighter space 

 in the middle of the cavity. Inequalities, cr 

 nodular protuberances, are soon observable 

 in this layer ; and it speedily becomes broken 

 up into numerous little isolated portions, 

 individualization of these commencing at 

 the summit of the sporange and becoming 

 completed gradually from above downwards. 

 The end-cell is now a clavate sporange filled 

 with numerous polyhedral or globular new 

 "primordial cells," in the development of 

 which from the contents of the general 

 parent-cell no trace of nuclei or " special 

 parent-cells " can be detected ; their size is 

 about 1-2700 of an inch; and they have 



