182 Agricultural Gazette. 



presents a rounded terminus, which, inasmuch as the tail is destitute of 

 glands (?), contains no aperture. The anus is not conspicuous and there is 

 710 sign of a bursa. The two equal, linear, acute, nearly straight spicula are 

 wider and fusiform in the proximal third and are about twice as long as the 

 tail or considerably longer than the anal diameter.* There are traces of 

 accessory organs. The ductus ejaculatorius seems to be at least three to four 

 times as long as the spicula. The testicle (or testicles ; 1 do not know 

 whether the male apparatus is single or double) appear.s to extend forward to 

 near the median oesophageal bulb. The spermatozoa are large and spherical 

 with conspicuous darker nuclei lying in the centre of tlie i-emaining trans- 

 lucent protoplasm. IV Fig. 6 represents a cross-section of the male taken 

 from the region of the vas dcforeus, and shows the spermatozoa in situ, and 

 also the size and relative position of the intestine. The left side of the 

 figure is dorsal. 



It only remains to say, concerning the structure of the male, that the tail, 

 when seen in the dorsal or ventral aspect, presents a different contour from 

 that shown when it is seen in profile, appearing in the former case to be 

 somewhat concave-conoid. 



Prom the foregoing description it will be seen that the males resulting 

 from the moult in which the remarkable change of form occurs, are in all 

 respects mature, being supplied with testicles and eopulatory apparatus. 

 "With regard to the copulation I will venture to offer one or two suggestions. 

 It is manifest that if the mature male had the form shown in Fig. 3, he 

 would be much less perfectly adapted to making his way through the tissues 

 of the root in which he has developed than if his form were a more slender 

 •one, and I can have no doubt that this fact explains the remarkable return 

 to a slender form, shown in Fig. G. The female, so far as I know (and I 

 have examined quite a number, perhaps twenty), continues in the course 

 already indicated — that is to say, never returns to a slender form, but, con- 

 tinuing the line of development shown in I, II, III, Fig. 1, becomes a motion- 

 less sac, whose sole object is the production of eggs. It wouldseem, then, that 

 the copulation must take place inside the tissues of the ])lant infested, 

 and that the males are enabled, by their return to the slender form, to make 

 their way about in search of their obese and motionless female companions. 

 The only other tenable hypotliesis is that the males leave the plant, and that 

 copulation occurs in the soil. This supposition Las nothing in its favour 

 ■which is not also in favour of the first supposition, and against it may be set 

 lip the two following suggestions : — (I) The female is not known to return 

 to a slender form, and probably, after having once entered a root, never 

 returns to the soil. (2) If the female docs not return to the soil (and 

 I must regard this as fairly well established by my observations) the only 

 copulation that could occur in the soil would be between the males which 

 Jiad made their way outward and the females which had not yet entered. 

 'These females, however, do not, so far as I have observed, possess a vulva or 

 jinj sexual apparatus beyond a rudiment consisting of a single cell, and are 

 therefore i)ieapabie of copulating. What dim light my researches have shed 

 on the subject compels me therefore to adopt the supposition that the males 

 on assuming the slender adult form seek out and fertilize the females lying 

 in the surrounding tissues. This supposition is possibly fortified by the 

 fibsence of a bursa in the male, though I am not certain that the argument 

 possesses much force. The fact is that the allied species {Tylenchi) possess 

 a more or less complete bursa. There are reasons for regarding the bursa 

 as a structure whoso function is the attachment of the male to the female 



* The reader will hove trust the text and not the Illustration, Fig. C (p s) gi\ cs but a poor idea of the 

 Jippearance of the spicula. 



