620 



NA TURh 



[April 28, 1898 



they would fall easy victims to enemies much weaker and slower 

 than themselves. 



On the other hand, we learn from Dufour that the species 

 found in Algeria are exempt from the attacks of the Mason 

 wasps, which, as is well known, in that and in all countries 

 fearlessly attack and destroy numbers of the largest spiders, and 

 could, without difficulty, catch the fleetest Solpuga in the world. 

 The reason for this freedom from persecution is not quite clear, 

 unless it is to b*e explained by the fact that the Solpuga is too 

 formidable a foe for the wasp to tackle. That this may well be 

 the case is rendered intelligible by the reflection that the large 

 lycosiform and mygaloid spiders fall easy victims because, owing 

 to feebleness of vision and lack of activity, they are not quick 

 enough to elude the final swoop of the wasp. The Solpugas, on 

 the other hand, as compared with the spiders, are exceedingly 

 agile and keen-siglited. Moreover, when on the defence, they 

 have a habit, as described by Dr. Walter, of turning up the 

 abdomen, so as to protect that vulnerable part, and extending 

 the legs forwards and upwards in such a way as to present to the 

 foe a pair of gaping jaws surmounted by five pairs of strong 

 limbs armed with long bristles, stout spines and sharp claws. 

 Small wonder if under the circumstances the wasps think dis- 

 cretion the better part of valour. 



The last peculiarity to be mentioned is the presence on the 

 inner surface of the jaws of some strong horny ridges, which by 

 mutual friction emit a harsh grating noise. In some genera 

 these ridges are scarcely at all developed : in others they are 

 very pronounced. That the sound is produced in the way 

 described under the stimulus of sudden fear or irritation was long 

 ago pointed out by Hutton, and even before him by Pallas ; and, 

 touching its function, one can only suppose that, like analogous 

 organs found in the rattlesnake and in some of the largest spiders 

 and scorpions, it acts as an advertisement of the whereabouts of 

 the Solpuga, and as a warning to enemies to keep a respectful 

 distance. R. I. PococK. 



THE LABOULBENIACE^ : A NEW FIELD 

 OF STUDY AMONG FUNGI. 



'T*IIE knowledge of most botanists of the group of Fungi 

 ''■ here under treatment is probably confined to the brief 

 description given of them by De Bary, under the head of 

 "Doubtful Ascomycetes," where Peyritsch's figures of Stig- 

 mdtomyces Baeri are reproduced. 



Since 1884, when De Bary's " Fungi" appeared, the investi- 

 gation of the group has, however, proceeded apace ; and 

 whereas at that time hardly more than a dozen species had 

 been distinguished. Dr. Thaxter considers that no fewer than 

 150 species belonging to 30 genera are now known. Almost 

 all of these additions are due to Dr. Thaxter's investigations, 

 and have already been announced, from time to time, in a 

 series of papers emanating from the Cryptogamic Laboratory 

 of Harvard University. 



The first to observe one of these Fungi was probably the 

 entomologist Laboulbene, in whose honour Labottlbenia roiigetii 

 was named by Montagne and C. Robin. The earliest descrip- 

 tion came from Robin in the " Histoire Naturelle des Vegetaux^ 

 Parasites" in 1853. II. Karsten {1869) and Peyritsch (1871-75) 

 followed with a more detailed treatment of the morphological 

 characters of the group, and still later Berlese, Giard, Istvanffi, 

 and Thaxter, have in turn added to our knowledge of the 

 family. 



The Laboulbeniaceae are, without exception, entomogenous, 

 and occur upon species of beetles and flies almost exclusively. 

 They are attached to the chitin of the insect by only a minute 

 foot, by means of which, however, they absorb all the nutri- 

 ment they require for their development. Upon examination 

 with a hand-lens, they have the appearance of hairs or bristles 

 of a dark colour, standing out vertically from the substratum. 

 As they seldom exceed half a millimetre in length, it is not 

 surprising that they easily escape the notice of entomologist 

 and mycologist alike. 



Their morphological characters present features of unusual 

 interest, inasmuch as they seem to exhibit a marked sexuality, 

 and that of a peculiar type. The male cells are non-motile 

 spermatia, arising for the most part endogenously, but in 



1. "Contributions toward* a Monograph of the Laboulbeniaceae." By 

 Roland Thaxter. (Memoirs of the American Academy of Arts and 

 Sciences, vol. xii. No. 3, December 1896. Pp. 242, pis. 26.) 



NO. 1487. VOL. 57] 



certain genera abstricted exogenously, as in the case of the 

 Floridere. These spermatia become attached to trichogynes, 

 whose cell-wall appears to have the same gelatinous consistence 

 as have those of the Floridere. In some genera, these tricho- 

 gynes become branched and multicellular ; in a few cases they 

 bend over to come into contact with spermatia in situ, and 

 then straighten again, carrying off a detached spermatium. 

 Bearing the trichogyne is a " trichophore," itself resting on a 

 "carpogenous" cell. From this latter there are ultimately budded 

 off four or eight asci, each containing, when mature, four or 

 eight usually septate ascospores, the whole being enclosed in 

 a fusiform fructification, recalling the perithecium of a Pyre- 

 nomycete. It seems impossible to resist the impression that 

 the asci arise as the result of an act of fertilisation, though the 

 details of the process have not been observed. That the 

 Laboulbeniacese are to be included among Ascomycetes can no 

 longer be doubtful, and their morphology, when considered in 

 connection with the observations of De Bary, Janczewski, 

 Stahl, and more recently Harper, lend support to the view that 

 sexuality persists in this class of Fungi It is difficult to imagine 

 how otherwise Brefeld can account for the structure of Laboul- 

 beniacese, when his researches have extended thus far. 



The similarity in the method of fertilisation with that existing 

 in FIoridei« is very marked. For the occurrence of a receptive 

 trichogyne and detached non-motile spermatia among Fungi, 

 Stahl's observations had already prepared us, though it has 

 been denied that the structures called by these names in Colle- 

 maceje, have the sexual significance they have been shown to 

 have in Floridere. The analogy of the similar organs in Laboul- 

 beniaccK with those of Floridese would seem to be beyond 

 doubt. A further startling analogy with Floridese is found in 

 the occurrence of a single conspicuous pit in the walls separating 

 successive cells of the hyphse ; and, as in Floridere, these have 

 already been utilised in tracing the genetic connection of the 

 cells of the thallus. Although Thaxter, on account of these 

 similarities, does not regard the derivation of Laboulbeniacese 

 from Floridese, as unworthy of consideration, it is improbable 

 that they indicate anything more than similarities of adaptation, 

 which often occur in widely separated groups. 



Of the 250 different species of insects on which these Fungi 

 have been found parasitic, 241 are Coleoptera, and of these the 

 majority are aquatic or riparian in habit. Of the 7 dipterous 

 host-species one is the common house-fly, which is frequently 

 infested with Siigmatomyces Baeri in the neighbourhood of 

 Vienna. The single termite affected came from Africa, and the 

 single acarid from Paraguay. Though most of the Laboul- 

 beniacese yet described are exclusively North American, 19 

 European species are known, and some accompany their hosts 

 into two or three continents. It is probable that the family will 

 be found to be numerous in species, and widely distributed in 

 range. No British locality for a single species is given in Dr. 

 Thaxter's work, and no British writer seems to have yet made 

 any contribution to the literature of the group. In Dr. Cooke's 

 " Vegetable Wasps and Plant Worms," published in 1892, the 

 species then described by Thaxter and others are enumerated, 

 but no discovery of any of these in Britain seems to have been 

 known to the author. It is highly improbable, however, that 

 none of the parasites occur on any of the more than 3000 British 

 species of Coleoptera. 



Though these plants do not at present appear likely to become 

 of any economic importance, yet it is clear that they are of ex- 

 ceptional morphological and physiological interest ; and Prof. 

 Thaxter has earned our gratitude for the persistence with which 

 he has pursued their study, and for the ability and skill with 

 which he has described and portrayed them. The work forms 

 a worthy successor to the author's monograph on " The Ento- 

 mophthorese of the United States." R. W. P. 



THE BOLOMETER} 



T N the number of the American Journal of Science for March 

 1881, there appeared an article descriptive of the actinic 

 balance (since called the Bolometer), an instrument which has 

 gained acceptance among physicists as a useful aid in the study 

 of radiant heat. It was, it may be remembered, originally 

 devised by the writer to discriminate the heat in any small 

 portion of the grating spectrum, but it has since found wider 

 applications. 



1 Reprinted from \\i& American Journal of Science, .\pril. (Communicated 

 by the Author.) 



