J. SAUNDERS — NOTES ON THE MYCETOZOA. 139 



vironmont to rnablo them to flourish, ^[oistiire is essential, with a 

 temperature not too low. Frost apparently drives them into 

 hitlinu;, whilst too nuicli dry heat desiccates the surface of the 

 matrix, and tlius compels them to seek sustenance in the moist 

 interior of tlie decayed vegetation. This may be rotten wood or 

 decaying leaves, but in any case it must be organic. None of tliem 

 contain chlorophyll, and hence they have not the power to assimi- 

 late food from the inorganic substances of the earth, or from the 

 impalpable gases of the air. There are cases on record in which 

 the sporangia, or fruiting heads, have been found on lead pipes and 

 old shoes, but these do not imply that they fed on such indigestible 

 articles, but that, having previously absorbed sufficient nutriment, 

 it is a matter of indifference to what materials they may creep in 

 order to form their capsules. The plasmodium stage is essentially 

 the feeding one, and during this period the protoplasmic contents 

 are particularly rich in formative materials. One may even suggest 

 that there is a distant analogy between this life-period of the 

 organism and the larval stage of the Lepidoptera. 



The Plasmodia, having no protective cell-covering, are peculiarly 

 sensitive to injury by contact. They are really wall-less proto- 

 plasm, and hence the slightest touch from the incautious tiuger 

 causes local death, although the other portions may remain healthy. 

 The fact that their contents are not restricted by cell-walls may 

 account for their excessive mobility, enabling them to insinuate 

 themselves into the interstices of wood that may be only in an 

 incipient stage of decay, and also into the honeycomb-like cavities 

 of the fungus [Irpex) on which they often occur. Their course 

 over this fungus is always indicated by a marked change in it; its 

 normal hue is a creamy white, but, when plasmodium has passed 

 over it, it changes to a dirty drab, and is apparently in a moribund 

 condition. The discoloration of the food-plant may also be partly 

 due to a slimy substance which is left by the Mycetozoon as it 

 shifts its position, as though it threw off the waste material that 

 would otherwise accumulate in its own substance. This rejection 

 of useless contents is particularly marked in the fruiting stage. 



Although so singularly sensitive to contact, the plasmodium will 

 endure strange vicissitudes without injury. It may be dried up 

 till it is apparently hard and tough, in which condition it may be 

 kept for an indefinite period — weeks and even months — after 

 which, by the application of moisture, with careful treatment, it 

 may be resuscitated and will become as active as ever. 



During the closing part of the summer of the past year we were 

 desirous to obtain some plasmodium, but were unable to do so 

 owing to the drjmess of the season A request for some of it was 

 sent to an esteemed correspondent, who is a specialist in this de- 

 partment of science. In reply, a small portion of desiccated plas- 

 modium attached to a fungus was forwarded in a pill- box. This 

 had been di-ied artificially several weeks previously. Wishing to 

 see if it would revive, it was placed in a shallow glazed vessel four 

 or five inches wide. On the opposite side of the vessel a portion of 



