The South Australian Naturalist. 



Excursion, 21/8/20.— The leader, Mr. E. H. Ising, took a 

 large party from Blackwood to Eden to study the flora, with 

 special reference to orchids. Only two orchids were seen in 

 flower ; it was too early for the main spring blooms. A paper 

 was read by the leader, who referred to Australian orchids, and 

 mentioned the two chief classes — those that grow in the ground 

 (terrestrial) and those that grow on other plants (epiphytical). 

 The latter did not grow as parasites ; they merely attach them- 

 selves to tree trunks (usually) for support only. Their roots 

 are aerial, and obtain their food from the air. South Australian 

 specimens were, with one possible exception, terrestrial. Their 

 colours varied from white to pink, red and maroon; cream, yel- 

 low and brown, shades of blue, heliotrope and green, in various 

 combinations. Some were of delightful colours, while others 

 were green and inconspicuous. The shapes of the flowers were 

 many and varied ; the tongue, or labellum, was the petal which 

 usuall.v attracted attention by its irregular and novel outline. 

 Some had their tongue beaded, others curled up or hinged and 

 very sensitive, so that they could trap an unwary insect ; while 

 quite reversed or upside down was a feature of others. Some 

 of the most handsome, the Thelymitras, does not possess the 

 usual fantastic tongue, it being about the same as the other 

 floral parts. Other native flowers were recognised by the 

 leader. 



Excursion, 4/9/20.— Mr. A. H. Elston, F.E.S., led an excur- 

 sion to Bridgewater. It was not a suitable day for the study 

 of insects, the weather being dull and showery, and few of 

 interest Avere seen, but there were everywhere the signs of 

 their existence. Mr. Elston drew attention to the various galls 

 to be seen on the Eucalypts and other plants, and explained 

 their origin and development. Midges, wasps, and flies were 

 mentioned as the insects chiefly responsible for the making of 

 galls, which may be defined as vegetable excrescences resulting 

 from insect activities, and usually sheltering the immature 

 stages of the producers. Some very good examples were seen 

 of insect galls that had begun their growth in the bud, and 

 therefore at a time when the plant tissues are plastic and more 

 easily modified, Avhilst others were seen that had developed 

 through the result of the continued stimulation by the gall- 

 makers themselves. Mr. Elston spoke of the fascination and 

 economic importance of this branch of the science, and said the 

 collection and study of plant galls is a field that is open to 

 many, specimens being found at all times of the year ; the study 

 embraces botany as well as entomology. 



