196 RESEARCHES ON FUNGI 



gave a list of all the species referred by other authors to this genus. 

 He considered P. crystalUnus and P. oedipus (Fig. 104, p. 209) to 

 be the only certain species ; P. roridus he regarded as doubtful, 

 P. lentiger he refers, wrongly, to P. oedipus, and P. anomalus he 

 places in the genus Ascophora by the name of A. Cesatii. 



In 1871 Cooke published the Handbook of British Fungi, but, 

 though he mentions the two conventional species, P. crystalUnus 

 and P. roridus, it is impossible to recognise exactly what he means 

 by the names. 



It was in 1872 that Klein (after a short note in 1870) gave to the 

 world his monograph " Zur Kenntniss des Pilobolus," a monument 

 of patient and minute investigation. In this he describes two 

 species, " P. crystalUnus " and " P. microsporus " ; under the 

 former name he says that he unites the P. crystalUnus and P. oedipus 

 of former authors. But, though he records his painstaking observa- 

 tions with great accuracy, in respect of the identification of his 

 specimens Klein was peculiarly unfortunate. His P. microsporus 

 is identical with P. roridus, and he was unacquainted with either the 

 true crystalUnus or the true oedipus. He had before his eyes, 

 without knowing it, another species hitherto undistinguished, to 

 which van Tieghem afterwards gave in his honour the name of 

 Pilobolus Kleinii. The spores of P. oedipus are yeUow, nearly 

 spherical, and surrounded by a thickened epispore ; those of 

 P. crystalUnus are ellipsoidal and nearly colourless. Now those of 

 P. Kleinii are also ellipsoidal, but of an orange-yeUow colour and 

 twice as long as those of P. crystalUnus ; in certain circumstances, 

 however, P. Kleinii bears sporangia containing nearly spherical 

 spores of the same colour but without a thickened epispore. It was 

 this abnormal state, to which I gave in my monograph of the Pilo- 

 bolidae the name forma sphaerospora, that led Klein erroneously 

 to imagine that he had met with forms intermediate between 

 oedipus and crystalUnus. The credit of clearing up this mistake 

 was due to van Tieghem (1876). 



In my own cultures, on many occasions, I found that the first 

 two or three days' crops of P. Kleinii bore small sporangia, contain- 

 ing roundish spores, of unequal size in the same sporangium. These, 

 however, could be distinguished at once by the want of the thickened 



